Vulnerability · Published Oct 1, 2026 · Assigned by GitHub_M
CVE-2026-103923KaTeX: Existing prototype pollution can bypass trust restrictions
Low 2.1
In plain English
A low-severity security flaw in KaTeX from KaTeX. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web. From 0.11.0 until 0.18.2, KaTeX uses ordinary JavaScript property access for the renderer options object, the trust setting, default and processor setting metadata, and namespace lookup and group restoration, allowing inherited properties to be treated as explicitly supplied values. When Object.prototype is already polluted or an attacker controls the options object's prototype, attacker-controlled mathematical expressions can use an inherited trust value to enable trusted rendering and produce links capable of user-interaction cross-site scripting or loading attacker-selected external resources in a consuming application that inserts unsanitized KaTeX output into a page. KaTeX does not itself create the prototype pollution, and rendering an expression alone does not execute script. This issue is fixed in version 0.18.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | node-katex | no fix listed | DEBIAN-CVE-2026-103923 |
| Debian:13 | node-katex | no fix listed | DEBIAN-CVE-2026-103923 |
| Debian:14 | node-katex | 0.16.10+~cs6.1.0-10 | DEBIAN-CVE-2026-103923 |
| Ubuntu:26.04:LTS | node-katex | no fix listed | UBUNTU-CVE-2026-103923 |
| Ubuntu:26.10 | node-katex | no fix listed | UBUNTU-CVE-2026-103923 |
| npm | katex | 0.18.2 | GHSA-238p-pmpm-9mq7 |
Affected products (as reported)
Weakness: CWE-807 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
References
- https://github.com/KaTeX/KaTeX/security/advisories/GHSA-238p-pmpm-9mq7 x_refsource_CONFIRM
- https://github.com/KaTeX/KaTeX/pull/4260 x_refsource_MISC
- https://github.com/KaTeX/KaTeX/commit/0adf7e77db6915d991803b29699f82b1ccf8d4f4 x_refsource_MISC
- https://github.com/KaTeX/KaTeX/releases/tag/v0.18.2 x_refsource_MISC