CVE-2026-39857 Information Disclosure via `choices`/`counts` Query Parameters Bypassing publicApiProjection Field Restrictions
Unauthenticated attackers can bypass field restrictions in ApostropheCMS to extract sensitive distinct values and counts from the database via query parameters.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39857?
CVE-2026-39857 is a medium-severity vulnerability in apostrophecms apostrophe, published on 15 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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 choices and counts query parameters of the REST API, where these query builders execute MongoDB distinct() operations that bypass the publicApiProjection restrictions intended to limit which fields are exposed publicly. The choices and counts parameters are processed via applyBuildersSafely before the projection is applied, and MongoDB's distinct operation does not respect projections, returning all distinct values directly. The results are returned in the API response without any filtering against publicApiProjection or removeForbiddenFields. An unauthenticated attacker can extract all distinct field values for any schema field type that has a registered query builder, including string, integer, float, select, boolean, date, slug, and relationship fields. Fields protected with viewPermission are similarly exposed, and the counts variant additionally reveals how many documents have each distinct value. Both the piece-type and page REST APIs are affected. This issue has been fixed in version 4.29.0.
Weakness: CWE-200
Which versions are affected by CVE-2026-39857?
2 open source packages ship an affected version, including apostrophe. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
apostrophe npm | All versions | 4.29.0 |
apostrophe npm | All versions | 4.29.0 |
Products include Apostrophecms Apostrophecms.
How do I fix CVE-2026-39857?
Upgrade apostrophe to 4.29.0 or later.
Is CVE-2026-39857 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39857 exists.
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- CVE-2026-32730 ApostropheCMS MFA/TOTP Bypass via Incorrect MongoDB Query in Bearer Token Middleware
- CVE-2026-40186 ApostropheCMS: sanitize-html allowedTags Bypass via Entity-Decoded Text in nonTextTags Elements
- CVE-2026-33889 ApostropheCMS: Stored XSS via CSS Custom Property Injection in `@apostrophecms/color-field` Escaping Style Tag Context
Sources
Also known as GHSA-c276-fj82-f2pq.