GHSA-vh4h-fvqf-q9wv – @cloudflare/workers-oauth-provider

Package

Manager: npm
Name: @cloudflare/workers-oauth-provider
Vulnerable Version: <0

Severity

Level: Medium

CVSS v3.1: N/A

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/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:Amber

EPSS: N/A pctlN/A

Details

Duplicate Advisory: @cloudflare/workers-oauth-provider PKCE bypass via downgrade attack # Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-qgp8-v765-qxx9. This link is maintained to preserve external references. # Original 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.

Metadata

Created: 2025-05-01T03:31:17Z
Modified: 2025-05-01T17:01:34Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/05/GHSA-vh4h-fvqf-q9wv/GHSA-vh4h-fvqf-q9wv.json
CWE IDs: ["CWE-287"]
Alternative ID: N/A
Finding: N/A
Auto approve: 0