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Vulnerability record · CVE-2026-27804 · published 26 February 2026

CVE-2026-27804: Parseplatform parse-server broken cryptographic algorithm vulnerability

Parseplatform · Parse Server

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.

9.3 CVSS 4.0 Critical EPSS 0.23% · top 87.4% CWE-327 · Broken cryptographic algorithmCWE-345 · Insufficient verification of data authenticity
9.3CVSS 4.0 base score
0.23%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References
17 Jun 2026Last modified by NVD

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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7 Patch
https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330 Patch
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 Release Notes
https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2 PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-27804), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.