CVE-2024-28244
KaTeX's maxExpand bypassed by Unicode sub/superscripts
Impact
### Impact KaTeX users who render untrusted mathematical expressions could encounter malicious input using `\def` or `\newcommand` 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 any of the characters `₊₋₌₍₎₀₁₂₃₄₅₆₇₈₉ₐₑₕᵢⱼₖₗₘₙₒₚᵣₛₜᵤᵥₓᵦᵧᵨᵩᵪ⁺⁻⁼⁽⁾⁰¹²³⁴⁵⁶⁷⁸⁹ᵃᵇᶜᵈᵉᵍʰⁱʲᵏˡᵐⁿᵒᵖʳˢᵗᵘʷˣʸᶻᵛᵝᵞᵟᵠᵡ` before passing them to KaTeX. (There is no easy workaround for the auto-render extension.) ### Details KaTeX supports an option named `maxExpand` which aims to prevent infinitely recursive macros from consuming all available memory and/or triggering a stack overflow error. Unfortunately, [support for "Unicode (sub|super)script characters"](https://github.com/KaTeX/KaTeX/commit/d8fc35e6a97f8e561c723b93ad275cf5a7f3094a) allows an attacker to bypass this limit. Each sub/superscript group instantiated a separate Parser with its own limit on macro executions, without inheriting the current count of macro executions from its parent. This has been corrected in KaTeX v0.16.10. ### 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
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | katex | >= 0.15.4, < 0.16.10 | 0.16.10 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Katex | Katex | from 0.15.4 before 0.16.10 |