Login Request a demo
Critical severity · published Feb 25, 2026
CVE-2026-27804
Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter
9.1
CVSS
0.2%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 10% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PA
parse-server · parse-community
>= 9.0.0, < 9.3.1-alpha.4; < 8.6.3 · source: vendor, NVD
Affected product
PA
parse-server
parse-community
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27804
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27804
Patch
https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7
Patch
https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330
Release Notes
https://github.com/parse-community/parse-server/releases/tag/8.6.3
Release Notes
https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4
Patch
https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2
More from parse-server
10.0
CVE-2026-30966
Parse Server role escalation and CLP bypass via direct `_Join` table write
9.8
CVE-2026-32248
Parse Server: Account takeover via operator injection in authentication data identifier
9.8
CVE-2026-31871
Parse Server has a SQL Injection via dot-notation sub-key name in `Increment` operation on PostgreSQL
9.8
CVE-2026-31856
Parse Server has a SQL injection via `Increment` operation on nested object field in PostgreSQL
9.8
CVE-2026-31840
Parse Server has a SQL injection via dot-notation field name in PostgreSQL