GHSA-vh4h-fvqf-q9wv
Suggest an improvement- Source
- https://github.com/advisories/GHSA-vh4h-fvqf-q9wv
- Import Source
- https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/05/GHSA-vh4h-fvqf-q9wv/GHSA-vh4h-fvqf-q9wv.json
- JSON Data
- https://api.osv.dev/v1/vulns/GHSA-vh4h-fvqf-q9wv
- Withdrawn
- 2025-05-01T17:01:33Z
- Published
- 2025-05-01T03:31:17Z
- Modified
- 2025-05-01T17:01:34Z
- Severity
-
- 5.3 (Medium) CVSS_V4 - 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 CVSS Calculator
- Summary
- Duplicate Advisory: @cloudflare/workers-oauth-provider PKCE bypass via downgrade attack
- Details
-
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This advisory has been withdrawn because it is a duplicate of GHSA-qgp8-v765-qxx9.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.
- Database specific
{ "cwe_ids": [ "CWE-287" ], "github_reviewed": true, "github_reviewed_at": "2025-05-01T17:01:33Z", "nvd_published_at": "2025-05-01T01:15:54Z", "severity": "MODERATE" }- References
Affected packages
npm / @cloudflare/workers-oauth-provider
Package
- Name
- @cloudflare/workers-oauth-provider
- View open source insights on deps.dev
- Purl
- pkg:npm/%40cloudflare/workers-oauth-provider