CVE-2024-28243

Impact

### 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)

Affected packages

Affected products

Weakness classification

References

• NVD record
• CVE.org record
• GitHub advisory
• https://github.com/KaTeX/KaTeX/commit/e88b4c357f978b1bca8edfe3297f0aa309bcbe34
• https://github.com/KaTeX/KaTeX/security/advisories/GHSA-64fm-8hw2-v72w
• https://github.com/github/advisory-database/pull/6777
• https://github.com/advisories/GHSA-64fm-8hw2-v72w
• https://nvd.nist.gov/vuln/detail/CVE-2024-28243