GHSA-G8R4-P96J-XFXC

Vulnerability from github – Published: 2021-04-16 19:53 – Updated: 2022-08-11 00:01
VLAI?
Summary
Grav's Twig processing allowing dangerous PHP functions by default
Details

Impact

Twig processing of static pages can be enabled in the front matter by any administrative user allowed to create or edit pages. As the Twig processor runs unsandboxed, this behavior can be used to gain arbitrary code execution and elevate privileges on the instance.

Patches

The issue was addressed by preventing dangerous functions from being called in Twig templates. A configuration option has been added to manually allow arbitrary PHP functions (system.twig.safe_functions) and filters (system.twig.safe_filters).

Futures major versions of Grav may disable this functionality by default.

Workarounds

Blocking access to the /admin path from untrusted sources will reduce the probability of exploitation.

References

  • https://portswigger.net/research/server-side-template-injection
  • https://blog.sonarsource.com/grav-cms-code-execution-vulnerabilities

For more information

If you have any questions or comments about this advisory, you can contact: - The original reporters, by sending an email to vulnerability.research [at] sonarsource.com; - The maintainers, by opening an issue on this repository.

Severity ?
8.4 (High)
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.7.10"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "getgrav/grav"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.7.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-29440"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-04-13T19:55:46Z",
    "nvd_published_at": "2021-04-13T20:15:00Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nTwig processing of static pages can be enabled in the front matter by any administrative user allowed to create or edit pages. \nAs the Twig processor runs unsandboxed, this behavior can be used to gain arbitrary code execution and elevate privileges on the instance.\n\n### Patches\n\nThe issue was addressed by preventing dangerous functions from being called in Twig templates. A configuration option has been added to manually allow arbitrary PHP functions (`system.twig.safe_functions`) and filters (`system.twig.safe_filters`). \n\nFutures major versions of Grav may disable this functionality by default. \n\n### Workarounds\n\nBlocking access to the `/admin` path from untrusted sources will reduce the probability of exploitation. \n\n### References\n\n- https://portswigger.net/research/server-side-template-injection\n- https://blog.sonarsource.com/grav-cms-code-execution-vulnerabilities\n\n### For more information\n\nIf you have any questions or comments about this advisory, you can contact:\n  - The original reporters, by sending an email to vulnerability.research [at] sonarsource.com;\n  - The maintainers, by opening an issue on this repository.",
  "id": "GHSA-g8r4-p96j-xfxc",
  "modified": "2022-08-11T00:01:25Z",
  "published": "2021-04-16T19:53:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getgrav/grav/security/advisories/GHSA-g8r4-p96j-xfxc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-29440"
    },
    {
      "type": "WEB",
      "url": "https://blog.sonarsource.com/grav-cms-code-execution-vulnerabilities"
    },
    {
      "type": "WEB",
      "url": "https://packagist.org/packages/getgrav/grav"
    },
    {
      "type": "WEB",
      "url": "http://packetstormsecurity.com/files/162987/Grav-CMS-1.7.10-Server-Side-Template-Injection.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Grav\u0027s Twig processing allowing dangerous PHP functions by default"
}


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  • 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.
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  • 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.