CVE-2026-33421

Workarounds

Use ACLs on individual objects to restrict read access instead of relying solely on CLP pointer permissions. ACLs are enforced by LiveQuery.

Parse Server's LiveQuery WebSocket interface does not enforce Class-Level Permission (CLP) pointer permissions (readUserFields and pointerFields). Any authenticated user can subscribe to LiveQuery events and receive real-time updates for all objects in classes protected by pointer permissions, regardless of whether the pointer fields on those objects point to the subscribing user. This bypasses the intended read access control, allowing unauthorized access to potentially sensitive data that is correctly restricted via the REST API.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2026-33421 has a CVSS score of 6.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.6.0-alpha.42, 8.6.53); upgrading removes the vulnerable code path.

Kodem intelligence

The LiveQuery server now enforces pointer permissions on each event. After the existing check passes (which defers pointer permissions by design), the fix checks whether any configured pointer field on the object points to the subscribing user. Events for objects that don't match are silently skipped, consistent with how ACL mismatches are handled.

1. What is CVE-2026-33421? CVE-2026-33421 is a high-severity incorrect authorization vulnerability in parse-server (npm), affecting versions >= 9.0.0, < 9.6.0-alpha.42. It is fixed in 9.6.0-alpha.42, 8.6.53. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2026-33421? CVE-2026-33421 has a CVSS score of 6.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of parse-server are affected by CVE-2026-33421? parse-server (npm) versions >= 9.0.0, < 9.6.0-alpha.42 is affected.
4. Is there a fix for CVE-2026-33421? Yes. CVE-2026-33421 is fixed in 9.6.0-alpha.42, 8.6.53. Upgrade to this version or later.
5. Is CVE-2026-33421 exploitable, and should I be worried? Whether CVE-2026-33421 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-33421 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-33421?
   • Upgrade parse-server to 9.6.0-alpha.42 or later
   • Upgrade parse-server to 8.6.53 or later