Vulnerability details
CVE-2026-27804
Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter
Official 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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 9.3Critical | 4.0 | CVEProject cvelistV5 (CNA) (GitHub_M) | 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 |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| parse-community | parse-server | < 8.6.3 | CVEProject cvelistV5 (CNA) |
| parse-community | parse-server | >= 9.0.0, < 9.3.1-alpha.4 | CVEProject cvelistV5 (CNA) |
References and advisories
5- https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2 x_refsource_CONFIRM
- https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7 x_refsource_MISC
- https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330 x_refsource_MISC
- https://github.com/parse-community/parse-server/releases/tag/8.6.3 x_refsource_MISC
- https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4 x_refsource_MISC
Details
- Published
- 2026-02-26
- Last updated
- 2026-02-26
- State
- Published
- Assigner (CNA)
- GitHub_M
Exploit prediction (EPSS)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- None
- Technical impact
- Total
Weaknesses (CWE)
- CWE-327Use of a Broken or Risky Cryptographic Algorithm
- CWE-345Insufficient Verification of Data Authenticity