Vulnerability · Published Apr 15, 2026 · Assigned by GitHub_M

CVE-2026-33888ApostropheCMS: publicApiProjection Bypass via `project` Query Builder in Piece-Type REST API

Medium 5.3

In plain English

A medium-severity incorrect authorization in apostrophe from apostrophecms. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.5%top 56.1% 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. Versions 4.28.0 and prior contain an authorization bypass vulnerability in the getRestQuery method of the @apostrophecms/piece-type module, where the method checks whether a MongoDB projection has already been set before applying the admin-configured publicApiProjection. An unauthenticated attacker can supply a project query parameter in the REST API request, which is processed by applyBuildersSafely before the permission check, pre-populating the projection state and causing the publicApiProjection to be skipped entirely. This allows disclosure of any field on publicly queryable documents that the administrator explicitly restricted from the public API, such as internal notes, draft content, or metadata. Exploitation is trivial, requiring only appending query parameters to a public URL with no authentication. This issue has been fixed in version 4.29.0.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	apostrophe	4.29.0	GHSA-xhq9-58fw-859p

Affected products (as reported)

Vendor	Product	Versions
apostrophecms	apostrophe	< 4.29.0

Weakness: CWE-863, CWE-200 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

References

https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-xhq9-58fw-859p x_refsource_CONFIRM
https://github.com/apostrophecms/apostrophe/commit/00d472804bb622df36a761b6f2cf2b33b2d4ce80 x_refsource_MISC
https://github.com/apostrophecms/apostrophe/commit/6c2b548dec2e3f7a82e8e16736603f4cd17525aa x_refsource_MISC