CVE-2026-27804
CriticalSummary
Parse Server prior to versions 8.6.3 and 9.1.1-alpha.4 is vulnerable to an attack where an unauthenticated attacker can forge a Google authentication token with 'alg: "none"', allowing them to log in as any user linked to a Google account without knowing their credentials.
Risk Assessment
Organizations with Google authentication enabled are at risk of unauthorized access to user accounts, potentially leading to serious security breaches and data loss.
Recommendation
It is recommended to disable Google authentication until an upgrade to version 8.6.3 or 9.1.1-alpha.4 is possible to minimize the risk of attack.
Original NVD description (English source)
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.