CVE-2026-27804CRITICAL 9.1EPSS p7.3%
CVE-2026-27804CVE-2026-27804
Description
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.3 and 9.1.1-alpha.4, an unauthenticated attacker can forge a Google authentication token with `alg: "none"` to log in as any user linked to a Google account, without knowing their credentials. All deployments with Google authentication enabled are affected. The fix in versions 8.6.3 and 9.1.1-alpha.4 hardcodes the expected `RS256` algorithm instead of trusting the JWT header, and replaces the Google adapter's custom key fetcher with `jwks-rsa` which rejects unknown key IDs. As a workaround, dsable Google authentication until upgrading is possible.
Scoring
| CVSS 3.1 | 9.1 (CRITICAL) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| EPSS | 0.18% probability of exploitation · percentile 7.3% · 2026-06-19T12:03:05Z |
| Published | 2026-02-26 |
| Last modified | 2026-03-04 |
Underlying weaknesses· 2
References
- https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7
- https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330
- https://github.com/parse-community/parse-server/releases/tag/8.6.3
- https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4
- https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2
2
| Type | Target | Confidence | Tier |
|---|---|---|---|
| Weakness | Use of a Broken or Risky Cryptographic Algorithmcwe-327 | 0% | live |
| Weakness | Insufficient Verification of Data Authenticitycwe-345 | 0% | live |
Related by meaning· 6
Nearest entities by semantic similarity across the cs-graph corpus.