Vulnerability-Lookup

CVE-2026-62672 (GCVE-0-2026-62672)

Vulnerability from cvelistv5 – Published: 2026-08-19 15:44 – Updated: 2026-08-19 18:00

Title

Grav: Authenticated ReDoS via regex_replace in Twig Sandbox

Summary

Grav is a file-based Web platform. Prior to 2.0.4, Grav allowlists the regex_replace filter and function in system/config/security.yaml, and GravExtension::regexReplace() passes an editor-controlled pattern directly to preg_replace(). When security.twig_content.process_enabled is enabled, an authenticated page editor can publish a catastrophically backtracking pattern that consumes PHP worker CPU and denies service to site visitors. This issue is fixed in version 2.0.4.

Severity

6 (Medium)


                        
                          CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-19 18:00 UTC

CWE

CWE-1333 - Inefficient Regular Expression Complexity

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/getgrav/grav/security/advisori…	x_refsource_CONFIRM
https://github.com/getgrav/grav/commit/907116268a…	x_refsource_MISC
https://github.com/getgrav/grav/releases/tag/2.0.4	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
getgrav	grav	Affected: < 2.0.4	guessed

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2026-62672",
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          ],
          "url": "https://github.com/getgrav/grav/security/advisories/GHSA-37f3-6p89-6qr9"
        },
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      },
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    }
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    "dateReserved": "2026-07-14T20:22:04.394Z",
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          }
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                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
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                "version": "4.0",
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          },
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              ],
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}

FKIE_CVE-2026-62672

Vulnerability from fkie_nvd - Published: 2026-08-19 16:18 - Updated: 2026-09-09 21:13

Severity

6.0 (Medium) - CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/getgrav/grav/commit/907116268ad4f48be7472c57f64981918578599a
	security-advisories@github.com	https://github.com/getgrav/grav/releases/tag/2.0.4
	security-advisories@github.com	https://github.com/getgrav/grav/security/advisories/GHSA-37f3-6p89-6qr9
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/getgrav/grav/security/advisories/GHSA-37f3-6p89-6qr9

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "grav",
          "vendor": "getgrav",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.0.4"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Grav is a file-based Web platform. Prior to 2.0.4, Grav allowlists the regex_replace filter and function in system/config/security.yaml, and GravExtension::regexReplace() passes an editor-controlled pattern directly to preg_replace(). When security.twig_content.process_enabled is enabled, an authenticated page editor can publish a catastrophically backtracking pattern that consumes PHP worker CPU and denies service to site visitors. This issue is fixed in version 2.0.4."
    }
  ],
  "id": "CVE-2026-62672",
  "lastModified": "2026-09-09T21:13:25.910",
  "metrics": {
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          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.0,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
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          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
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    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getgrav/grav/commit/907116268ad4f48be7472c57f64981918578599a"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getgrav/grav/releases/tag/2.0.4"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getgrav/grav/security/advisories/GHSA-37f3-6p89-6qr9"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/getgrav/grav/security/advisories/GHSA-37f3-6p89-6qr9"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
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        {
          "lang": "en",
          "value": "CWE-1333"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
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}

GHSA-37F3-6P89-6QR9

Vulnerability from github – Published: 2026-09-02 14:50 – Updated: 2026-09-17 16:34

Summary

Grav: Authenticated ReDoS via regex_replace in Twig Sandbox

Details

Summary

The regex_replace filter and function are allowlisted in Grav's Twig content sandbox. When Twig processing in page content is enabled security.twig_content.process_enabled: true, authenticated page editors can supply a catastrophically backtracking PCRE pattern, causing unbounded CPU consumption and denying service to the entire web server process.

Details

The Twig sandbox allowlists, defined in system/config/security.yaml, explicitly include regex_replace in both the filter and function permission lists:

Source: system/config/security.yaml

twig_sandbox:
  allowed_filters:
    # ...
    - regex_replace    #  user-controlled pattern allowed in sandbox
  allowed_functions:
    # ...
    - regex_replace    #  same

The underlying implementation passes the caller-controlled $pattern directly into PHP's preg_replace() without any pattern complexity validation:

Source: system/src/Grav/Common/Twig/Extension/GravExtension.php:1317-1319

public function regexReplace($subject, $pattern, $replace, $limit = -1)
{
    return preg_replace($pattern, $replace, $subject, $limit);
}

When twig_content.process_enabled is true, page body content is sandboxed but can use any allowlisted filter. An editor who embeds a catastrophic backtracking pattern causes the PCRE engine to enter exponential time complexity, consuming 100% CPU until the PHP process is killed or the request times out.

Conditions required: 1. security.twig_content.process_enabled: true (opt-in, false by default on fresh 2.0 installs) 2. security.twig_sandbox.enabled: true (default) - the function is reachable under sandbox 3. Attacker must have page edit access (authenticated contributor / editor role)

PoC

Configuration prerequisite - enable Twig in content:

# user/config/security.yaml
twig_content:
  process_enabled: true

Payload — embed in any Grav page body with process: { twig: true } in frontmatter:

---
title: Test
process:
  twig: true
---
{{ 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab'|regex_replace('/^(a+)+$/', '') }}

Or as a function call in a page where the editor has Twig access:

{{ regex_replace('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab', '/^(a+)+$/', '') }}

Result: The PHP-FPM worker (or CLI server process) enters catastrophic PCRE backtracking. On a 2 GHz host, a 32-character string with the above pattern will exhaust one CPU core for seconds to minutes. With a slightly longer string, the time grows exponentially.

Impact

Vulnerability type: Regular Expression Denial of Service - ReDoS

Who is impacted: Server availability. Any Grav installation where: - An editor-role account exists (or has been compromised), AND - The operator has enabled twig_content.process_enabled: true

An attacker with page-edit access can render the site unresponsive for all visitors by publishing a page with a catastrophic regex. On single-worker PHP configurations this is a complete outage. On multi-worker setups, multiple concurrent page renders of the malicious page can saturate all workers.

Severity

6.0 (Medium)


                  
                    CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "getgrav/grav"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-62672"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-02T14:50:57Z",
    "nvd_published_at": "2026-08-19T16:18:20Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nThe `regex_replace` filter and function are allowlisted in Grav\u0027s Twig content sandbox. When Twig processing in page content is enabled `security.twig_content.process_enabled: true`, authenticated page editors can supply a catastrophically backtracking PCRE pattern, causing unbounded CPU consumption and denying service to the entire web server process.\n\n---\n\n### Details\n\nThe Twig sandbox allowlists, defined in `system/config/security.yaml`, explicitly include `regex_replace` in both the filter and function permission lists:\n\n**Source: `system/config/security.yaml`**\n\n```yaml\ntwig_sandbox:\n  allowed_filters:\n    # ...\n    - regex_replace    #  user-controlled pattern allowed in sandbox\n  allowed_functions:\n    # ...\n    - regex_replace    #  same\n```\n\nThe underlying implementation passes the caller-controlled `$pattern` directly into PHP\u0027s `preg_replace()` without any pattern complexity validation:\n\n**Source: `system/src/Grav/Common/Twig/Extension/GravExtension.php:1317-1319`**\n\n```php\npublic function regexReplace($subject, $pattern, $replace, $limit = -1)\n{\n    return preg_replace($pattern, $replace, $subject, $limit);\n}\n```\n\nWhen `twig_content.process_enabled` is `true`, page body content is sandboxed but can use any allowlisted filter. An editor who embeds a catastrophic backtracking pattern causes the PCRE engine to enter exponential time complexity, consuming 100% CPU until the PHP process is killed or the request times out.\n\n**Conditions required**:\n1. `security.twig_content.process_enabled: true` (opt-in, `false` by default on fresh 2.0 installs)\n2. `security.twig_sandbox.enabled: true` (default) - the function is reachable under sandbox\n3. Attacker must have page edit access (authenticated contributor / editor role)\n\n---\n\n### PoC\n\n**Configuration prerequisite** - enable Twig in content:\n\n```yaml\n# user/config/security.yaml\ntwig_content:\n  process_enabled: true\n```\n\n**Payload** \u2014 embed in any Grav page body with `process: { twig: true }` in frontmatter:\n\n```\n---\ntitle: Test\nprocess:\n  twig: true\n---\n{{ \u0027aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab\u0027|regex_replace(\u0027/^(a+)+$/\u0027, \u0027\u0027) }}\n```\n\nOr as a function call in a page where the editor has Twig access:\n\n```twig\n{{ regex_replace(\u0027aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab\u0027, \u0027/^(a+)+$/\u0027, \u0027\u0027) }}\n```\n\n**Result**: The PHP-FPM worker (or CLI server process) enters catastrophic PCRE backtracking. On a 2 GHz host, a 32-character string with the above pattern will exhaust one CPU core for seconds to minutes. With a slightly longer string, the time grows exponentially.\n\n---\n\n### Impact\n\n**Vulnerability type**: Regular Expression Denial of Service - ReDoS\n\n**Who is impacted**: Server availability. Any Grav installation where:\n- An editor-role account exists (or has been compromised), AND\n- The operator has enabled `twig_content.process_enabled: true`\n\nAn attacker with page-edit access can render the site unresponsive for all visitors by publishing a page with a catastrophic regex. On single-worker PHP configurations this is a complete outage. On multi-worker setups, multiple concurrent page renders of the malicious page can saturate all workers.\n\n---",
  "id": "GHSA-37f3-6p89-6qr9",
  "modified": "2026-09-17T16:34:43Z",
  "published": "2026-09-02T14:50:57Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getgrav/grav/security/advisories/GHSA-37f3-6p89-6qr9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-62672"
    },
    {
      "type": "WEB",
      "url": "https://github.com/getgrav/grav/commit/907116268ad4f48be7472c57f64981918578599a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/getgrav/grav"
    },
    {
      "type": "WEB",
      "url": "https://github.com/getgrav/grav/releases/tag/2.0.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Grav: Authenticated ReDoS via regex_replace in Twig Sandbox"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

CVE-2026-62672 (GCVE-0-2026-62672)

FKIE_CVE-2026-62672

GHSA-37F3-6P89-6QR9

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Details

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