GHSA-4Q3H-VP4R-PRV2

Vulnerability from github – Published: 2026-02-25 23:00 – Updated: 2026-02-25 23:00
VLAI?
Summary
Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter
Details

Impact

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.

Patches

The fix 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.

Workarounds

Disable Google authentication until you can upgrade.

References

  • GitHub advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2
  • Fixed in Parse Server 9.3.1-alpha.4: https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4
  • Fixed in Parse Server 8.6.3: https://github.com/parse-community/parse-server/releases/tag/8.6.3
Severity ?
9.3 (Critical)
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
Show details on source website
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 9.3.1-alpha.3"
      },
      "package": {
        "ecosystem": "npm",
        "name": "parse-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "9.0.0"
            },
            {
              "fixed": "9.3.1-alpha.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 8.6.2"
      },
      "package": {
        "ecosystem": "npm",
        "name": "parse-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.6.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27804"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-327",
      "CWE-345"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-25T23:00:49Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Impact\n\nAn 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.\n\n### Patches\n\nThe fix hardcodes the expected `RS256` algorithm instead of trusting the JWT header, and replaces the Google adapter\u0027s custom key fetcher with `jwks-rsa` which rejects unknown key IDs.\n\n### Workarounds\n\nDisable Google authentication until you can upgrade.\n\n### References\n\n- GitHub advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2\n- Fixed in Parse Server 9.3.1-alpha.4: https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4\n- Fixed in Parse Server 8.6.3: https://github.com/parse-community/parse-server/releases/tag/8.6.3",
  "id": "GHSA-4q3h-vp4r-prv2",
  "modified": "2026-02-25T23:00:49Z",
  "published": "2026-02-25T23:00:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/parse-community/parse-server"
    },
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/releases/tag/8.6.3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.