Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
ApostropheCMS versions before 4.34.0 accept color field values that begin with a valid rgb() or hsl() color followed by arbitrary text, because the TinyColor validation is not anchored at the end of the string. An authenticated user with edit permission can store HTML after such a prefix, which executes in the browsers of visitors and administrators who view the page, enabling stored cross-site scripting. The package is fixed in version 4.34.0, so upgrading to that version or later is the remedy.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 5.4 | Medium | 3.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0030, the 23rd percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 13:33 UTC First seen by agentprime
- 31 Oct 2026, 13:33 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-vmgj-9cwm-cf3h
- OSV: GHSA-vmgj-9cwm-cf3h
- github.com/apostrophecms/apostrophe/security/advisories/GHSA-vmgj-9cwm-cf3h
- nvd.nist.gov/vuln/detail/CVE-2026-112951
- github.com/apostrophecms/apostrophe/commit/06e4b377f3c360f9e89c32dccd7e505ad5ddf498
- github.com/apostrophecms/apostrophe/commit/40b989b1a9dd23d30029b8ce7668634265cfe5ea
- github.com/apostrophecms/apostrophe
- github.com/apostrophecms/apostrophe/releases/tag/[email protected]