🛡️ CVE-2025-4144
🔴 CVSS 9.8 — Critical ✅ No Known Exploit CWE-287 NVD
9.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

PKCE was implemented in the OAuth implementation in workers-oauth-provider that is part of MCP framework https://github.com/cloudflare/workers-mcp . However, it was found that an attacker could cause the check to be skipped. Fixed in: https://github.com/cloudflare/workers-oauth-provider/pull/27 https://github.com/cloudflare/workers-oauth-provider/pull/27 Impact: PKCE is a defense-in-depth mechanism against certain kinds of attacks and was an optional extension in OAuth 2.0 which became required in the OAuth 2.1 draft. (Note that the MCP specification requires OAuth 2.1.). This bug completely bypasses PKCE protection.

Details

Severity Critical
CVSS Score 9.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE CWE-287
Public Exploit âś… No
Source NVD
Published 2025-05-01
Updated 2026-06-02
Modified 2025-05-01

Affected Packages

Software From version Fixed in
@cloudflare/workers-oauth-provider — —
workers-oauth-provider — —

Similar Threats

Exploit Protection

Help block exploit attempts

BotEraser is designed to detect and help reduce malicious bot traffic that may target known vulnerabilities on your site.

Try BotEraser Free →

No credit card required  Â·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.