Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M

CVE-2026-112951ApostropheCMS: Color field validation bypass allows stored XSS via HTML appended after rgb()/hsl() prefix

Medium 5.4

In plain English

A medium-severity cross-site scripting in apostrophe from apostrophecms. Proof-of-concept exploit code is public. 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.

Severity (CVSS 3.1)5.4Medium

Exploit odds (30 days)0.3%top 76.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

ApostropheCMS is an open-source Node.js content management system. Prior to 4.34.0, the color field accepts trailing content after a valid rgb() or hsl() prefix because its TinyColor validation does not require the entire value to match a color. An authenticated user with edit rights can store arbitrary HTML after a valid color prefix. When the stored value is rendered, the payload executes, resulting in stored XSS. This issue is fixed in version 4.34.0.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	apostrophe	4.34.0	GHSA-vmgj-9cwm-cf3h

Affected products (as reported)

Vendor	Product	Versions
apostrophecms	apostrophe	< 4.34.0

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

References

https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-vmgj-9cwm-cf3h x_refsource_CONFIRM
https://github.com/apostrophecms/apostrophe/commit/06e4b377f3c360f9e89c32dccd7e505ad5ddf498 x_refsource_MISC
https://github.com/apostrophecms/apostrophe/commit/40b989b1a9dd23d30029b8ce7668634265cfe5ea x_refsource_MISC
https://github.com/apostrophecms/apostrophe/releases/tag/apostrophe@4.34.0 x_refsource_MISC