CVE-2026-27804CWE-327CWE-345

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

Critical · published February 25, 2026

CVSS v4.0
9.3
EPSS
0%
Percentile
13.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
9.3 · CRITICAL
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
EPSS
0.00237 · 13.8th percentile
Weaknesses
CWE-327 · Use of a Broken or Risky Cryptographic Algorithm; CWE-345 · Insufficient Verification of Data Authenticity
Published
2026-02-25T23:48Z
EPSS history
Timeline
  • 25 FEB 23:48Z
    Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter
    cvelistv5