CVE-2026-27804

Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter

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.

Scores

Weaknesses (CWE)

• CWE-327
• CWE-345

Advisories

• GHSA-4q3h-vp4r-prv2 — Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter

European references

• ENISA EUVD · EUVD-2026-8774
• GCVE · GCVE-0-2026-27804

Affected configurations (NVD CPE)

• cpe:2.3:a:parseplatform:parse-server:*:*:*:*:*:node.js:*:* < 8.6.3
• cpe:2.3:a:parseplatform:parse-server:*:*:*:*:*:node.js:*:* ≥ 9.0.0 < 9.3.1
• cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha1:*:*:*:node.js:*:*
• cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha2:*:*:*:node.js:*:*
• cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha3:*:*:*:node.js:*:*

Affected products

References

• https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2
• 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

Sources