Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M

CVE-2026-113659ApostropheCMS: Client-side Prototype Pollution in apos.http.parseQuery leading to DOM-based XSS against authenticated users

Medium 6.1

In plain English

A medium-severity cross-site scripting in apostrophe from apostrophecms. 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 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.1Medium

Exploit odds (30 days)0.3%top 71.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

ApostropheCMS is an open-source Node.js content management system. Prior to 4.33.0, an unauthenticated attacker can send a crafted link whose query string is automatically parsed by apos.http.parseQuery when an authenticated victim loads a page with the admin bundle. The parser accepts the special __proto__, constructor, and prototype path keys, allowing browser prototype mutation that can reach an unsafe DOM sink and execute script in the victim's session; anonymous visitors do not load the affected admin context. This issue is fixed in version 4.33.0.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	apostrophe	4.33.0	GHSA-m2m5-rw3w-cwmj

Affected products (as reported)

Vendor	Product	Versions
apostrophecms	apostrophe	< 4.33.0

Weakness: CWE-79, CWE-1321 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-m2m5-rw3w-cwmj x_refsource_CONFIRM
https://github.com/apostrophecms/apostrophe/commit/9500b8b0e1d630d5e07fbb5fd2c25ed0943845ce x_refsource_MISC
https://github.com/apostrophecms/apostrophe/commit/f84fd41cbf6c22eb8d0008fc9c25df1f7130b350 x_refsource_MISC
https://github.com/apostrophecms/apostrophe/releases/tag/apostrophe@4.33.0 x_refsource_MISC