GHSA-cvr6-37gx-v8wc
MEDIUMGHSA-cvr6-37gx-v8wc is a medium-severity (CVSS 6.5) CWE-674 vulnerability in katex. O3 Security confirms whether GHSA-cvr6-37gx-v8wc is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
KaTeX's maxExpand bypassed by Unicode sub/superscripts
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
katexnpmDescription
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" 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
- Email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | katex | ≥ 0.15.4&&< 0.16.10 | 0.16.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for katex. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update katex to 0.16.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cvr6-37gx-v8wc is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-cvr6-37gx-v8wc is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-cvr6-37gx-v8wc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-cvr6-37gx-v8wc in your dependencies?
O3 detects GHSA-cvr6-37gx-v8wc across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.