CWE-295
AllowedImproper Certificate Validation
Abstraction: Base · Status: Draft
The product does not validate, or incorrectly validates, a certificate.
1917 vulnerabilities reference this CWE, most recent first.
GHSA-FF6C-W6QF-7XQC
Vulnerability from github – Published: 2026-05-07 02:06 – Updated: 2026-06-08 23:18Summary
The CSS Parser gem does not validate HTTPS connections, allowing a Man-in-the-Middle (MITM) attacker to inject or modify CSS content when stylesheets are loaded via HTTPS. The connection is established with OpenSSL::SSL::VERIFY_NONE, meaning any HTTPS certificate—even entirely untrusted—will be accepted without validation.
Details
In lib/css_parser/parser.rb, the HTTP client sets:
https://github.com/premailer/css_parser/blob/3f91e8db7547fac50ab50cb7f9920f785f722740/lib/css_parser/parser.rb#L646
http.verify_mode = OpenSSL::SSL::VERIFY_NONE
As a result, the library does not validate the authenticity of HTTPS connections and does not protect against man-in-the-middle attacks. Any attacker in a position to intercept network traffic can inject or modify CSS loaded via HTTPS URLs without detection or warning.
PoC
- Set up a test Ruby project that uses the CSS Parser gem and loads an external stylesheet over HTTPS.
- Use a local proxy (such as mitmproxy or Burp Suite) to intercept outgoing HTTPS requests.
- Present a fake self-signed certificate to the client.
- Inject custom CSS into the intercepted HTTPS response.
The request will succeed and the injected CSS will be delivered to the application, as the connection is not validated.
References
https://github.com/premailer/css_parser/issues/185
Impact
Applications using CSS Parser to load remote stylesheets over HTTPS are vulnerable to CSS injection and content manipulation, regardless of the trust status of the remote server. All users who use CSS Parser to fetch external CSS over HTTPS may be impacted.
Credit
This vulnerability was uncovered by @JLLeitschuh of the @braze-inc security team.
{
"affected": [
{
"package": {
"ecosystem": "RubyGems",
"name": "css_parser"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.1.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "RubyGems",
"name": "css_parser"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.22.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-44312"
],
"database_specific": {
"cwe_ids": [
"CWE-295",
"CWE-829"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-07T02:06:49Z",
"nvd_published_at": "2026-05-14T17:16:22Z",
"severity": "MODERATE"
},
"details": "### Summary\n\nThe CSS Parser gem does not validate HTTPS connections, allowing a Man-in-the-Middle (MITM) attacker to inject or modify CSS content when stylesheets are loaded via HTTPS. The connection is established with `OpenSSL::SSL::VERIFY_NONE`, meaning any HTTPS certificate\u2014even entirely untrusted\u2014will be accepted without validation.\n\n### Details\n\nIn `lib/css_parser/parser.rb`, the HTTP client sets:\nhttps://github.com/premailer/css_parser/blob/3f91e8db7547fac50ab50cb7f9920f785f722740/lib/css_parser/parser.rb#L646\n\n```ruby\nhttp.verify_mode = OpenSSL::SSL::VERIFY_NONE\n```\n\nAs a result, the library does not validate the authenticity of HTTPS connections and does not protect against man-in-the-middle attacks. Any attacker in a position to intercept network traffic can inject or modify CSS loaded via HTTPS URLs without detection or warning.\n\n### PoC\n\n1. Set up a test Ruby project that uses the CSS Parser gem and loads an external stylesheet over HTTPS.\n2. Use a local proxy (such as mitmproxy or Burp Suite) to intercept outgoing HTTPS requests.\n3. Present a fake self-signed certificate to the client.\n4. Inject custom CSS into the intercepted HTTPS response.\n \nThe request will succeed and the injected CSS will be delivered to the application, as the connection is not validated.\n\n### References\n \nhttps://github.com/premailer/css_parser/issues/185\n\n### Impact\n\nApplications using CSS Parser to load remote stylesheets over HTTPS are vulnerable to CSS injection and content manipulation, regardless of the trust status of the remote server. All users who use CSS Parser to fetch external CSS over HTTPS may be impacted.\n\n### Credit\n\nThis vulnerability was uncovered by @JLLeitschuh of the @braze-inc security team.",
"id": "GHSA-ff6c-w6qf-7xqc",
"modified": "2026-06-08T23:18:03Z",
"published": "2026-05-07T02:06:49Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/premailer/css_parser/security/advisories/GHSA-ff6c-w6qf-7xqc"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44312"
},
{
"type": "WEB",
"url": "https://github.com/premailer/css_parser/issues/185"
},
{
"type": "WEB",
"url": "https://github.com/premailer/css_parser/commit/35e689c904225add78e0c488cf04bad052666449"
},
{
"type": "WEB",
"url": "https://github.com/premailer/css_parser/commit/e0c95d5abe91b237becb90ff316531a6547ada18"
},
{
"type": "PACKAGE",
"url": "https://github.com/premailer/css_parser"
},
{
"type": "WEB",
"url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/css_parser/CVE-2026-44312.yml"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "CSS Parser: Improper Certificate Validation allows MITM injection of remote CSS content"
}
GHSA-FFGC-36M3-C5GF
Vulnerability from github – Published: 2022-05-13 01:26 – Updated: 2022-05-13 01:26Google Chrome before 14.0.835.163 does not perform an expected pin operation for a self-signed certificate during a session, which has unspecified impact and remote attack vectors.
{
"affected": [],
"aliases": [
"CVE-2011-2874"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2011-09-19T12:02:00Z",
"severity": "MODERATE"
},
"details": "Google Chrome before 14.0.835.163 does not perform an expected pin operation for a self-signed certificate during a session, which has unspecified impact and remote attack vectors.",
"id": "GHSA-ffgc-36m3-c5gf",
"modified": "2022-05-13T01:26:52Z",
"published": "2022-05-13T01:26:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2011-2874"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/69892"
},
{
"type": "WEB",
"url": "https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14454"
},
{
"type": "WEB",
"url": "http://code.google.com/p/chromium/issues/detail?id=95917"
},
{
"type": "WEB",
"url": "http://googlechromereleases.blogspot.com/2011/09/stable-channel-update_16.html"
},
{
"type": "WEB",
"url": "http://osvdb.org/75567"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-FFMR-63F5-V2QX
Vulnerability from github – Published: 2022-05-13 01:06 – Updated: 2022-05-13 01:06Coordinate Plus App for Android 1.0.2 and earlier and Coordinate Plus App for iOS 1.0.2 and earlier do not verify SSL certificates.
{
"affected": [],
"aliases": [
"CVE-2016-4840"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-04-21T14:59:00Z",
"severity": "MODERATE"
},
"details": "Coordinate Plus App for Android 1.0.2 and earlier and Coordinate Plus App for iOS 1.0.2 and earlier do not verify SSL certificates.",
"id": "GHSA-ffmr-63f5-v2qx",
"modified": "2022-05-13T01:06:13Z",
"published": "2022-05-13T01:06:13Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2016-4840"
},
{
"type": "WEB",
"url": "http://jvn.jp/en/jp/JVN06920277/index.html"
},
{
"type": "WEB",
"url": "http://jvndb.jvn.jp/en/contents/2016/JVNDB-2016-000133.html"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/92314"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-FFR6-2835-468G
Vulnerability from github – Published: 2025-06-06 18:30 – Updated: 2025-06-18 18:30An improper certificate validation vulnerability has been reported to affect File Station 5. If exploited, the vulnerability could allow remote attackers who have gained user access to compromise the security of the system.
We have already fixed the vulnerability in the following versions: File Station 5 5.5.6.4791 and later and later
{
"affected": [],
"aliases": [
"CVE-2025-29884"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-06-06T16:15:25Z",
"severity": "HIGH"
},
"details": "An improper certificate validation vulnerability has been reported to affect File Station 5. If exploited, the vulnerability could allow remote attackers who have gained user access to compromise the security of the system.\n\nWe have already fixed the vulnerability in the following versions:\nFile Station 5 5.5.6.4791 and later\n and later",
"id": "GHSA-ffr6-2835-468g",
"modified": "2025-06-18T18:30:32Z",
"published": "2025-06-06T18:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-29884"
},
{
"type": "WEB",
"url": "https://www.qnap.com/en/security-advisory/qsa-25-09"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-FFRG-8PGR-8693
Vulnerability from github – Published: 2023-12-12 12:30 – Updated: 2023-12-12 12:30A vulnerability has been identified in SINEC INS (All versions < V1.0 SP2 Update 2). Affected products do not properly validate the certificate of the configured UMC server. This could allow an attacker to intercept credentials that are sent to the UMC server as well as to manipulate responses, potentially allowing an attacker to escalate privileges.
{
"affected": [],
"aliases": [
"CVE-2023-48427"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-12-12T12:15:14Z",
"severity": "HIGH"
},
"details": "A vulnerability has been identified in SINEC INS (All versions \u003c V1.0 SP2 Update 2). Affected products do not properly validate the certificate of the configured UMC server. This could allow an attacker to intercept credentials that are sent to the UMC server as well as to manipulate responses, potentially allowing an attacker to escalate privileges.",
"id": "GHSA-ffrg-8pgr-8693",
"modified": "2023-12-12T12:30:54Z",
"published": "2023-12-12T12:30:54Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-48427"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-077170.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-FGPW-Q4C2-RRGC
Vulnerability from github – Published: 2022-05-24 17:25 – Updated: 2023-01-27 21:31An issue was discovered in NLnet Labs Routinator 0.1.0 through 0.7.1. It allows remote attackers to bypass intended access restrictions or to cause a denial of service on dependent routing systems by strategically withholding RPKI Route Origin Authorisation ".roa" files or X509 Certificate Revocation List files from the RPKI relying party's view.
{
"affected": [],
"aliases": [
"CVE-2020-17366"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-08-05T22:15:00Z",
"severity": "MODERATE"
},
"details": "An issue was discovered in NLnet Labs Routinator 0.1.0 through 0.7.1. It allows remote attackers to bypass intended access restrictions or to cause a denial of service on dependent routing systems by strategically withholding RPKI Route Origin Authorisation \".roa\" files or X509 Certificate Revocation List files from the RPKI relying party\u0027s view.",
"id": "GHSA-fgpw-q4c2-rrgc",
"modified": "2023-01-27T21:31:10Z",
"published": "2022-05-24T17:25:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-17366"
},
{
"type": "WEB",
"url": "https://github.com/NLnetLabs/routinator/issues/319"
},
{
"type": "WEB",
"url": "https://github.com/NLnetLabs/routinator/releases/tag/v0.8.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-FGQ2-WJJ2-9C78
Vulnerability from github – Published: 2022-05-13 01:28 – Updated: 2022-05-13 01:28The (1) update and (2) package-installation features in MODX Revolution 2.5.4-pl and earlier do not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and trigger the execution of arbitrary code via a crafted certificate.
{
"affected": [],
"aliases": [
"CVE-2017-7322"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-03-30T07:59:00Z",
"severity": "HIGH"
},
"details": "The (1) update and (2) package-installation features in MODX Revolution 2.5.4-pl and earlier do not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and trigger the execution of arbitrary code via a crafted certificate.",
"id": "GHSA-fgq2-wjj2-9c78",
"modified": "2022-05-13T01:28:57Z",
"published": "2022-05-13T01:28:57Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-7322"
},
{
"type": "WEB",
"url": "https://mazinahmed.net/services/public-reports/ModX%20-%20Responsible%20Disclosure%20-%20January%202017.pdf"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/97228"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-FGVJ-4M6X-J67F
Vulnerability from github – Published: 2022-05-24 17:17 – Updated: 2024-11-20 15:30A missing verification of the TLS host in Nextcloud Mail 1.1.3 allowed a man in the middle attack.
{
"affected": [],
"aliases": [
"CVE-2020-8156"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-05-12T13:15:00Z",
"severity": "MODERATE"
},
"details": "A missing verification of the TLS host in Nextcloud Mail 1.1.3 allowed a man in the middle attack.",
"id": "GHSA-fgvj-4m6x-j67f",
"modified": "2024-11-20T15:30:48Z",
"published": "2022-05-24T17:17:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-8156"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KC6HLX5SG4PZO6Y54D2LFJ4ATG76BKOP"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KC6HLX5SG4PZO6Y54D2LFJ4ATG76BKOP"
},
{
"type": "WEB",
"url": "https://nextcloud.com/security/advisory/?id=NC-SA-2020-020"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:L",
"type": "CVSS_V3"
}
]
}
GHSA-FHHX-R983-44XC
Vulnerability from github – Published: 2022-03-30 00:00 – Updated: 2022-11-29 23:03Jenkins Proxmox Plugin 0.6.0 and earlier disables SSL/TLS certificate validation globally for the Jenkins controller JVM when configured to ignore SSL/TLS issues.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "org.jenkins-ci.plugins:proxmox"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.7.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-28142"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": true,
"github_reviewed_at": "2022-11-29T23:03:10Z",
"nvd_published_at": "2022-03-29T13:15:00Z",
"severity": "MODERATE"
},
"details": "Jenkins Proxmox Plugin 0.6.0 and earlier disables SSL/TLS certificate validation globally for the Jenkins controller JVM when configured to ignore SSL/TLS issues.",
"id": "GHSA-fhhx-r983-44xc",
"modified": "2022-11-29T23:03:10Z",
"published": "2022-03-30T00:00:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-28142"
},
{
"type": "PACKAGE",
"url": "https://github.com/jenkinsci/proxmox-plugin"
},
{
"type": "WEB",
"url": "https://www.jenkins.io/security/advisory/2022-03-29/#SECURITY-2081"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2022/03/29/1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "SSL/TLS certificate validation globally disabled by Jenkins Proxmox Plugin"
}
GHSA-FHJP-88MM-6Q8P
Vulnerability from github – Published: 2022-05-17 02:44 – Updated: 2025-04-20 03:37The Interval International app 3.3 through 3.5.1 for iOS does not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.
{
"affected": [],
"aliases": [
"CVE-2017-8941"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-05-15T18:29:00Z",
"severity": "MODERATE"
},
"details": "The Interval International app 3.3 through 3.5.1 for iOS does not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.",
"id": "GHSA-fhjp-88mm-6q8p",
"modified": "2025-04-20T03:37:44Z",
"published": "2022-05-17T02:44:00Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-8941"
},
{
"type": "WEB",
"url": "https://medium.com/%40chronic_9612/follow-up-76-popular-apps-confirmed-vulnerable-to-silent-interception-of-tls-protected-data-64185035029f"
},
{
"type": "WEB",
"url": "https://medium.com/@chronic_9612/follow-up-76-popular-apps-confirmed-vulnerable-to-silent-interception-of-tls-protected-data-64185035029f"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation
Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
Mitigation
If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
CAPEC-459: Creating a Rogue Certification Authority Certificate
An adversary exploits a weakness resulting from using a hashing algorithm with weak collision resistance to generate certificate signing requests (CSR) that contain collision blocks in their "to be signed" parts. The adversary submits one CSR to be signed by a trusted certificate authority then uses the signed blob to make a second certificate appear signed by said certificate authority. Due to the hash collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the adversary's second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority.
CAPEC-475: Signature Spoofing by Improper Validation
An adversary exploits a cryptographic weakness in the signature verification algorithm implementation to generate a valid signature without knowing the key.