Paper/Archive/CVE-2026-27804

CVE-2026-27804

parse-community parse-server — Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter

CVSS 9.3 (CNA)9.3 / 10 × 3027.9 Not in CISA KEV+300.0 EPSS percentile 10.0.100 × 202.0 No public exploit+100.0 SSVC exploitation: none+100.0

Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource

parse-server>= 9.0.0, < 9.3.1-alpha.4–CNA

parse-server< 8.6.3–CNA

Scores by source

GitHub_M (CNA)9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

NVD9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refgithub.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2 refgithub.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7 refgithub.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330 refgithub.com/parse-community/parse-server/releases/tag/8.6.3 refgithub.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4