GHSA-64FM-8HW2-V72W

Vulnerability from github – Published: 2024-03-25 19:38 – Updated: 2024-03-25 22:31
VLAI?
Summary
KaTeX's maxExpand bypassed by `\edef`
Details

Impact

KaTeX users who render untrusted mathematical expressions could encounter malicious input using \edef that causes a near-infinite loop, despite setting maxExpand to avoid such loops. This can be used as an availability attack, where e.g. a client rendering another user's KaTeX input will be unable to use the site due to memory overflow, tying up the main thread, or stack overflow.

Patches

Upgrade to KaTeX v0.16.10 to remove this vulnerability.

Workarounds

Forbid inputs containing the substring "\\edef" before passing them to KaTeX. (There is no easy workaround for the auto-render extension.)

Details

KaTeX supports an option named maxExpand which prevents infinitely recursive macros from consuming all available memory and/or triggering a stack overflow error. However, what counted as an "expansion" is a single macro expanding to any number of tokens. The expand-and-define TeX command \edef can be used to build up an exponential number of tokens using only a linear number of expansions according to this definition, e.g. by repeatedly doubling the previous definition. This has been corrected in KaTeX v0.16.10, where every expanded token in an \edef counts as an expansion.

For more information

If you have any questions or comments about this advisory: * Open an issue or security advisory in the KaTeX repository * Email us at katex-security@mit.edu

Severity ?
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "katex"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.10.0-beta"
            },
            {
              "fixed": "0.16.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-28243"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-606",
      "CWE-674"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-03-25T19:38:18Z",
    "nvd_published_at": "2024-03-25T20:15:07Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nKaTeX users who render untrusted mathematical expressions could encounter malicious input using `\\edef` that causes a near-infinite loop, despite setting `maxExpand` to avoid such loops. This can be used as an availability attack, where e.g. a client rendering another user\u0027s KaTeX input will be unable to use the site due to memory overflow, tying up the main thread, or stack overflow.\n\n### Patches\nUpgrade to KaTeX v0.16.10 to remove this vulnerability.\n\n### Workarounds\nForbid inputs containing the substring `\"\\\\edef\"` before passing them to KaTeX.\n(There is no easy workaround for the auto-render extension.)\n\n### Details\nKaTeX supports an option named `maxExpand` which prevents infinitely recursive macros from consuming all available memory and/or triggering a stack overflow error. However, what counted as an \"expansion\" is a single macro expanding to any number of tokens. The expand-and-define TeX command `\\edef` can be used to build up an exponential number of tokens using only a linear number of expansions according to this definition, e.g. by repeatedly doubling the previous definition. This has been corrected in KaTeX v0.16.10, where every expanded token in an `\\edef` counts as an expansion.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue or security advisory in the [KaTeX repository](https://github.com/KaTeX/KaTeX/)\n* Email us at [katex-security@mit.edu](mailto:katex-security@mit.edu)",
  "id": "GHSA-64fm-8hw2-v72w",
  "modified": "2024-03-25T22:31:55Z",
  "published": "2024-03-25T19:38:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/KaTeX/KaTeX/security/advisories/GHSA-64fm-8hw2-v72w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-28243"
    },
    {
      "type": "WEB",
      "url": "https://github.com/KaTeX/KaTeX/commit/e88b4c357f978b1bca8edfe3297f0aa309bcbe34"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/KaTeX/KaTeX"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "KaTeX\u0027s maxExpand bypassed by `\\edef`"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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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.



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