CVE-2024-28243: Katex KaTeX's MaxExpand Bypassed By `\edef` Vulnerability

MODERATE
Advisory Identifier: GHSA-64fm-8hw2-v72w
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CVSS 6.5
CWE-606 CWE-674
Published
Advisory Summary

CVE-2024-28243 is a MODERATE (CVSS 6.5) katex's maxexpand bypassed by `\edef` vulnerability (CWE-606: Unchecked Input for Loop Condition) affecting Katex libraries in the npm ecosystem. The issue involves katex's maxexpand bypassed by `\edef`. Remediation is available by upgrading affected packages to version 0.16.10.

CVE-2024-28243 at a Glance

CVE Identifier CVE-2024-28243
GHSA Identifier GHSA-64fm-8hw2-v72w
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-606: Unchecked Input for Loop Condition
Affected Product Katex
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2024-28243

To remediate this vulnerability, upgrade all affected Katex dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

katex fixed: 0.16.10 
npm install katex@0.16.10
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls katex

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2024-28243, inspect your project dependencies using npm:

npm ls katex

Analyze the terminal output to locate any version of Katex in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.16.10), your application is affected.

Note: The npm ls katex command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-606: Unchecked Input for Loop Condition, where the product does not properly check inputs that are used for loop conditions, potentially leading to a denial of service or other consequences because of excessive looping. In Katex, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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](https://github.com/KaTeX/KaTeX/) * Email us at [katex-security@mit.edu](mailto:katex-security@mit.edu)

CVE-2024-28243 Affected Katex Versions

1 component(s)
Fixed Versions:
0.16.10
Product / Package Ecosystem Affected Versions Fixed Version
katex
npm/katex
npm
≥ 0.12.0
< 0.16.10
0.16.10

References

GitHub Advisory / Wiki ADVISORY
https://github.com/KaTeX/KaTeX/security/advisories/GHSA-64fm-8hw2-v72w
NVD — CVE-2024-28243 NVD
https://nvd.nist.gov/vuln/detail/CVE-2024-28243
Katex Source Repository REPOSITORY
https://github.com/github/advisory-database/pull/6777
Security Fix Commit FIX COMMIT
https://github.com/KaTeX/KaTeX/commit/e88b4c357f978b1bca8edfe3297f0aa309bcbe34
Katex Source Repository REPOSITORY
https://github.com/KaTeX/KaTeX

Frequently Asked Questions

What is CVE-2024-28243?
CVE-2024-28243 is a security vulnerability in Katex involving KaTeX's maxExpand bypassed by `\edef` under CWE-606: Unchecked Input for Loop Condition.
Which Katex versions are affected?
Affected versions include releases prior to 0.16.10 across affected packages: katex.
What version fixes CVE-2024-28243?
Upgrading to 0.16.10 (or the latest patched release for your respective branch) resolves the vulnerability.
Is katex affected?
Yes, katex is affected in releases prior to 0.16.10. Upgrade your dependency to 0.16.10 or later.
What is the CVSS score of CVE-2024-28243?
CVE-2024-28243 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2024-28243?
CVE-2024-28243 is classified under CWE-606: Unchecked Input for Loop Condition (The product does not properly check inputs that are used for loop conditions, potentially leading to a denial of service or other consequences because of excessive looping.).
How can I check npm dependencies for CVE-2024-28243?
Run the dependency tree command: 'npm ls katex'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-64fm-8hw2-v72w",
  "modified" : "2026-02-05T15:26:49Z",
  "published" : "2024-03-25T19:38:18Z",
  "aliases" : [ "CVE-2024-28243" ],
  "summary" : "KaTeX's maxExpand bypassed by `\\edef`",
  "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's 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)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "katex"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.12.0"
      }, {
        "fixed" : "0.16.10"
      } ]
    } ]
  } ],
  "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/github/advisory-database/pull/6777"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/KaTeX/KaTeX/commit/e88b4c357f978b1bca8edfe3297f0aa309bcbe34"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/KaTeX/KaTeX"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-606", "CWE-674" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-03-25T19:38:18Z",
    "nvd_published_at" : "2024-03-25T20:15:07Z"
  }
}