ghsa-cpwx-vrp4-4pq7
Vulnerability from github
Published
2025-03-05 20:40
Modified
2025-03-05 21:54
Severity ?
5.4 (Medium) - CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Summary
Jinja2 vulnerable to sandbox breakout through attr filter selecting format method
Details

An oversight in how the Jinja sandboxed environment interacts with the |attr filter allows an attacker that controls the content of a template to execute arbitrary Python code.

To exploit the vulnerability, an attacker needs to control the content of a template. Whether that is the case depends on the type of application using Jinja. This vulnerability impacts users of applications which execute untrusted templates.

Jinja's sandbox does catch calls to str.format and ensures they don't escape the sandbox. However, it's possible to use the |attr filter to get a reference to a string's plain format method, bypassing the sandbox. After the fix, the |attr filter no longer bypasses the environment's attribute lookup.

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{
   affected: [
      {
         database_specific: {
            last_known_affected_version_range: "<= 3.1.5",
         },
         package: {
            ecosystem: "PyPI",
            name: "Jinja2",
         },
         ranges: [
            {
               events: [
                  {
                     introduced: "0",
                  },
                  {
                     fixed: "3.1.6",
                  },
               ],
               type: "ECOSYSTEM",
            },
         ],
      },
   ],
   aliases: [
      "CVE-2025-27516",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-1336",
      ],
      github_reviewed: true,
      github_reviewed_at: "2025-03-05T20:40:14Z",
      nvd_published_at: "2025-03-05T21:15:20Z",
      severity: "MODERATE",
   },
   details: "An oversight in how the Jinja sandboxed environment interacts with the `|attr` filter allows an attacker that controls the content of a template to execute arbitrary Python code.\n\nTo exploit the vulnerability, an attacker needs to control the content of a template. Whether that is the case depends on the type of application using Jinja. This vulnerability impacts users of applications which execute untrusted templates.\n\nJinja's sandbox does catch calls to `str.format` and ensures they don't escape the sandbox. However, it's possible to use the `|attr` filter to get a reference to a string's plain format method, bypassing the sandbox. After the fix, the `|attr` filter no longer bypasses the environment's attribute lookup.",
   id: "GHSA-cpwx-vrp4-4pq7",
   modified: "2025-03-05T21:54:05Z",
   published: "2025-03-05T20:40:14Z",
   references: [
      {
         type: "WEB",
         url: "https://github.com/pallets/jinja/security/advisories/GHSA-cpwx-vrp4-4pq7",
      },
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2025-27516",
      },
      {
         type: "WEB",
         url: "https://github.com/pallets/jinja/commit/90457bbf33b8662926ae65cdde4c4c32e756e403",
      },
      {
         type: "PACKAGE",
         url: "https://github.com/pallets/jinja",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
         type: "CVSS_V4",
      },
   ],
   summary: "Jinja2 vulnerable to sandbox breakout through attr filter selecting format method",
}


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