Parse Server vulnerable to session token exfiltration via redirectClassNameForKey query parameter

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N · score source

EPSS

• CVE-2026-30965: 1.36% estimated exploitation activity in the next 30 days; percentile 71.72 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A vulnerability in Parse Server's query handling allows an authenticated or unauthenticated attacker to exfiltrate session tokens of other users by exploiting the redirectClassNameForKey query parameter. Exfiltrated session tokens can be used to take over user accounts. The vulnerability requires the attacker to be able to create or update an object with a new relation field, which depends on the Class-Level Permissions of at least one class. Patches The fix applies the same security checks that normally protect class access after the query redirect, ensuring that queries redirected via redirectClassNameForKey are subject to the same restrictions as direct queries to the target class. Workarounds Set restrictive Class-Level Permissions to prevent clients from creating new fields on classes, specifically by disabling addField for public access and unauthenticated users. Note that this limits client functionality and does not fully eliminate the risk if a relation field pointing…

Published by the source

11 Mar 2026, 00:20 UTC

Last modified by the source

14 Mar 2026, 03:41 UTC

Source last checked

26 Oct 2026, 12:43 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-6r2j-cxgf-495f

2. Revision 3 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-6r2j-cxgf-495f

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-6r2j-cxgf-495f

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# Patch Next advisory brief: CVE-2026-30965

Advisory: Parse Server vulnerable to session token exfiltration via `redirectClassNameForKey` query parameter
IDs: CVE-2026-30965, GHSA-6r2j-cxgf-495f
Record: https://patchnext.com/advisories/cve-2026-30965 (revision 4, source checked 26 Oct 2026, 12:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: parse-server 9.5.2-alpha.8, 8.6.21. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm parse-server: affected >= 9.0.0-alpha.1, < 9.5.2-alpha.8; < 8.6.21; fixed in 8.6.21, 9.5.2-alpha.8

## Suggested inspection (read-only)
- `npm ls parse-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on parse-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-6r2j-cxgf-495f (GitHub-reviewed advisory GHSA-6r2j-cxgf-495f lists affected ranges: npm parse-server >=9.0.0-alpha.1 =0 <8.6.21)
- Verified: https://osv.dev/vulnerability/GHSA-6r2j-cxgf-495f (OSV record GHSA-6r2j-cxgf-495f lists affected ranges: npm parse-server >=9.0.0-alpha.1 =0 <8.6.21 (fixed))

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