CVE-2026-27804

9.3

CRITICAL CVSS 4.0

Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter

Overview

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.

Details

INFO

Published Date :

Feb. 26, 2026, 12:16 a.m.

Last Modified :

March 4, 2026, 3:09 a.m.

Remotely Exploit :

Yes !

Source :

[email protected]

Impact

Affected Products

The following products are affected by CVE-2026-27804 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID	Vendor	Product	Action
1	Parseplatform	parse-server

: Total Affected Vendor : 1 | Products : 1

Scoring

CVSS Scores

The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.

Score	Version	Severity	Vector	Exploitability Score	Impact Score	Source
	CVSS 3.1	CRITICAL				[email protected]
	CVSS 4.0	CRITICAL				[email protected]

Solution

Update Parse Server to fix Google authentication token forgery vulnerability.

Update Parse Server to version 8.6.3 or later.
Update Parse Server to version 9.1.1-alpha.4 or later.
Disable Google authentication if upgrading is not possible.

Public PoC/Exploit Available at Github

CVE-2026-27804 has a 2 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-27804.

URL	Resource
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	Patch Vendor Advisory

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-27804 is associated with the following CWEs:

CWE-327: Use of a Broken or Risky Cryptographic Algorithm

CWE-345: Insufficient Verification of Data Authenticity

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-27804 weaknesses.

CAPEC-20: Encryption Brute Forcing Encryption Brute Forcing CAPEC-97: Cryptanalysis Cryptanalysis CAPEC-459: Creating a Rogue Certification Authority Certificate Creating a Rogue Certification Authority Certificate CAPEC-473: Signature Spoof Signature Spoof CAPEC-475: Signature Spoofing by Improper Validation Signature Spoofing by Improper Validation CAPEC-608: Cryptanalysis of Cellular Encryption Cryptanalysis of Cellular Encryption CAPEC-614: Rooting SIM Cards Rooting SIM Cards CAPEC-111: JSON Hijacking (aka JavaScript Hijacking) JSON Hijacking (aka JavaScript Hijacking) CAPEC-141: Cache Poisoning Cache Poisoning CAPEC-142: DNS Cache Poisoning DNS Cache Poisoning CAPEC-148: Content Spoofing Content Spoofing CAPEC-218: Spoofing of UDDI/ebXML Messages Spoofing of UDDI/ebXML Messages CAPEC-384: Application API Message Manipulation via Man-in-the-Middle Application API Message Manipulation via Man-in-the-Middle CAPEC-385: Transaction or Event Tampering via Application API Manipulation Transaction or Event Tampering via Application API Manipulation CAPEC-386: Application API Navigation Remapping Application API Navigation Remapping CAPEC-387: Navigation Remapping To Propagate Malicious Content Navigation Remapping To Propagate Malicious Content CAPEC-388: Application API Button Hijacking Application API Button Hijacking CAPEC-665: Exploitation of Thunderbolt Protection Flaws Exploitation of Thunderbolt Protection Flaws CAPEC-701: Browser in the Middle (BiTM) Browser in the Middle (BiTM)

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

21-Twentyone/NVD-Docx-Generator

This repo contains the CVE automation project

Python

Updated: 6 days, 18 hours ago

0 stars 0 fork 0 watcher

Born at : March 9, 2026, 7:15 a.m. This repo has been linked 1 different CVEs too.

sebastianosrt/Public-reports-CVEs

None

Python

Updated: 1 week, 3 days ago

0 stars 0 fork 0 watcher

Born at : Oct. 26, 2025, 6:09 p.m. This repo has been linked 9 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-27804 vulnerability anywhere in the article.

Daily CyberSecurity

Algorithm Confusion: Critical 9.1 Flaw in Parse Server Allows Instant Google Account Takeover

Parse Server, a widely used open-source backend designed to be deployed on any infrastructure running Node.js and working alongside the Express web application framework, is currently affected by a hi ...

Published Date: Feb 26, 2026 (3 weeks ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-27804 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

Initial Analysis by [email protected]

Mar. 04, 2026

Action	Type	New Value
Added	CVSS V3.1	AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Added	CPE Configuration	OR cpe:2.3:a:parseplatform:parse-server::::::node.js:: versions up to (excluding) 8.6.3 cpe:2.3:a:parseplatform:parse-server::::::node.js:: versions from (including) 9.0.0 up to (excluding) 9.3.1 cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha1::::node.js:: cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha2::::node.js:: cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha3::::node.js::
Added	Reference Type	GitHub, Inc.: https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7 Types: Patch
Added	Reference Type	GitHub, Inc.: https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330 Types: Patch
Added	Reference Type	GitHub, Inc.: https://github.com/parse-community/parse-server/releases/tag/8.6.3 Types: Release Notes
Added	Reference Type	GitHub, Inc.: https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4 Types: Release Notes
Added	Reference Type	GitHub, Inc.: https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2 Types: Patch, Vendor Advisory

New CVE Received by [email protected]

Feb. 26, 2026

Action	Type	New Value
Added	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.
Added	CVSS V4.0	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:X/V:X/RE:X/U:X
Added	CWE	CWE-345
Added	CWE	CWE-327
Added	Reference	https://github.com/parse-community/parse-server/commit/9b94083accb7f3e72c6b8126c195c7a03dd2dfd7
Added	Reference	https://github.com/parse-community/parse-server/commit/9d5942d50e55c822924c27b05aa98f1393e7a330
Added	Reference	https://github.com/parse-community/parse-server/releases/tag/8.6.3
Added	Reference	https://github.com/parse-community/parse-server/releases/tag/9.3.1-alpha.4
Added	Reference	https://github.com/parse-community/parse-server/security/advisories/GHSA-4q3h-vp4r-prv2

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.