What’s Vulnerable › Vulnerabilities

CVE-2026-53609: Apostrophe has Server-Side Prototype Pollution in apos.util.set via patch operators that leads to process-wide authorization bypass

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-12 · updated 2026-10-25
• Weakness: CWE-1321

Description

ApostropheCMS is an open-source Node.js content management system. In versions up to and including 4.30.0, `apos.util.set()` traverses dot-notation paths without sanitizing `__proto__`, allowing an authenticated editor to write arbitrary values to `Object.prototype` via the `$pullAll` patch operator. A confirmed gadget in `publicApiCheck()` causes this to bypass authorization on all piece-type REST API endpoints for every subsequent unauthenticated request, for the lifetime of the Node.js process. As of time of publication, no known patched versions are available.

Affected products

• apostrophecms apostrophe: through 4.30.0

References

• https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-6h5j-32cf-4253
• https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-6h5j-32cf-4253

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