CVE-2026-27804: Parse Server Account Takeover Vulnerability

CRITICAL
Advisory Identifier: GHSA-4q3h-vp4r-prv2
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CWE-327 CWE-345
Published
Advisory Summary

CVE-2026-27804 is a CRITICAL account takeover vulnerability (CWE-327: Use of a Broken or Risky Cryptographic Algorithm) affecting Parse Server libraries in the npm ecosystem. The issue involves account takeover via jwt algorithm confusion in google auth adapter. Remediation is available by upgrading affected packages to version 9.3.1-alpha.4, 8.6.3.

CVE-2026-27804 at a Glance

CVE Identifier CVE-2026-27804
GHSA Identifier GHSA-4q3h-vp4r-prv2
Severity CRITICAL
CVSS v3.1 Base Score N/A
CWE Classification CWE-327: Use of a Broken or Risky Cryptographic Algorithm
Affected Product Parse Server
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-27804

To remediate this vulnerability, upgrade all affected Parse Server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

parse-server fixed: 9.3.1-alpha.4 
npm install parse-server@9.3.1-alpha.4
parse-server fixed: 8.6.3 
npm install parse-server@8.6.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls parse-server

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-27804, inspect your project dependencies using npm:

npm ls parse-server

Analyze the terminal output to locate any version of Parse Server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.3.1-alpha.4), your application is affected.

Note: The npm ls parse-server command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-327: Use of a Broken or Risky Cryptographic Algorithm, where the product uses a broken or risky cryptographic algorithm or protocol. In Parse Server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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

CVE-2026-27804 Affected Parse Server Versions

2 component(s)
Fixed Versions:
9.3.1-alpha.48.6.3
Product / Package Ecosystem Affected Versions Fixed Version
parse-server
npm/parse-server
npm
≥ 9.0.0
< 9.3.1-alpha.4
9.3.1-alpha.4
parse-server
npm/parse-server
npm
< 8.6.3
8.6.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2
NVD — CVE-2026-27804 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27804
Security Fix Commit FIX COMMIT
https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7
Security Fix Commit FIX COMMIT
https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330
Parse Server Source Repository REPOSITORY
https://github.com/parse-community/parse-server
Parse Server Release RELEASE
https://github.com/parse-community/parse-server/releases/tag/8.6.3
Parse Server Release RELEASE
https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4

Frequently Asked Questions

What is CVE-2026-27804?
CVE-2026-27804 is a security vulnerability in Parse Server involving Account takeover via JWT algorithm confusion in Google auth adapter under CWE-327: Use of a Broken or Risky Cryptographic Algorithm.
Which Parse Server versions are affected?
Affected versions include releases prior to 9.3.1-alpha.4, 8.6.3 across affected packages: parse-server.
What version fixes CVE-2026-27804?
Upgrading to 9.3.1-alpha.4, 8.6.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is parse-server affected?
Yes, parse-server is affected in releases prior to 9.3.1-alpha.4, 8.6.3. Upgrade your dependency to 9.3.1-alpha.4, 8.6.3 or later.
What CWE is associated with CVE-2026-27804?
CVE-2026-27804 is classified under CWE-327: Use of a Broken or Risky Cryptographic Algorithm (The product uses a broken or risky cryptographic algorithm or protocol.).
How can I check npm dependencies for CVE-2026-27804?
Run the dependency tree command: 'npm ls parse-server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4q3h-vp4r-prv2",
  "modified" : "2026-02-27T21:52:22Z",
  "published" : "2026-02-25T23:00:49Z",
  "aliases" : [ "CVE-2026-27804" ],
  "summary" : "Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter",
  "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's 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",
  "severity" : [ {
    "type" : "CVSS_V4",
    "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"
  } ],
  "affected" : [ {
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      }, {
        "fixed" : "9.3.1-alpha.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 9.3.1-alpha.3"
    }
  }, {
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      } ]
    } ],
    "database_specific" : {
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  "references" : [ {
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  }, {
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    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27804"
  }, {
    "type" : "WEB",
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  }, {
    "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-327", "CWE-345" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-25T23:00:49Z",
    "nvd_published_at" : "2026-02-26T00:16:25Z"
  }
}