GHSA-QGP8-V765-QXX9 @cloudflare/workers-oauth-provider PKCE bypass via downgrade attack

Summary PKCE was implemented in the OAuth implementation in workers-oauth-provider that is part of MCP framework. However, it was found that an attacker could cause the check to be skipped. Impact PKCE is a defense-in-depth mechanism against certain kinds of attacks and was an optional extension ...

@cloudflare/workers-oauth-provider PKCE bypass via downgrade attack

Summary PKCE was implemented in the OAuth implementation in workers-oauth-provider that is part of MCP framework. However, it was found that an attacker could cause the check to be skipped. Impact PKCE is a defense-in-depth mechanism against certain kinds of attacks and was an optional extension ...

@cloudflare/workers-oauth-provider missing validation of redirect_uri on authorize endpoint

Summary The OAuth implementation failed to check that redirecturi was among the allowed set for the clientid. Impact Under certain circumstances see below, if a victim had previously authorized with a server built on workers-oath-provider, and an attacker could later trick the victim into visitin...

GHSA-4PC9-X2FX-P7VJ @cloudflare/workers-oauth-provider missing validation of redirect_uri on authorize endpoint

Summary The OAuth implementation failed to check that redirecturi was among the allowed set for the clientid. Impact Under certain circumstances see below, if a victim had previously authorized with a server built on workers-oath-provider, and an attacker could later trick the victim into visitin...

@iflow-mcp/git-mcp (1.0.0), mtxuilib (>=0.8.11, <=0.8.17) potentially affected by CVE-2025-4143 via @cloudflare/workers-oauth-provider (0.0.2)

@cloudflare/workers-oauth-provider NPM version 0.0.2 is affected by a known vulnerability. The following packages have a transitive dependency on @cloudflare/workers-oauth-provider and may be impacted: - @iflow-mcp/git-mcp 1.0.0 - mtxuilib =0.8.11, =0.8.17 Source cves: CVE-2025-4143 Source...

Duplicate Advisory: @cloudflare/workers-oauth-provider missing validation of redirect_uri on authorize endpoint

Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-4pc9-x2fx-p7vj. This link is maintained to preserve external references. Original Description The OAuth implementation in workers-oauth-provider that is part of MCP framework...

GHSA-VH4H-FVQF-Q9WV 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...

GHSA-7CP4-JW97-3RC2 Duplicate Advisory: @cloudflare/workers-oauth-provider missing validation of redirect_uri on authorize endpoint

Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-4pc9-x2fx-p7vj. This link is maintained to preserve external references. Original Description The OAuth implementation in workers-oauth-provider that is part of MCP framework...

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...

CVE-2025-4143

The OAuth implementation in workers-oauth-provider that is part of MCP framework https://github.com/cloudflare/workers-mcp , did not correctly validate that redirecturi was on the allowed list of redirect URIs for the given client registration. Fixed in: ...

CVE-2025-4144

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...

CVE-2025-4144 PKCE bypass via downgrade attack

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...

CVE-2025-4144

CVE-2025-4144 affects Cloudflare’s MCP-based workers-oauth-provider. A flaw in the PKCE implementation allows an attacker to bypass PKCE verification, effectively bypassing PKCE protection. Descriptions across sources (Veracode, Red Hat, GHSA advisories, OSV) state that the OAuth check can be ski...

CVE-2025-4144 PKCE bypass via downgrade attack

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...

CVE-2025-4144

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...

CVE-2025-4143 Missing validation of redirect_uri on authorize endpoint

The OAuth implementation in workers-oauth-provider that is part of MCP framework https://github.com/cloudflare/workers-mcp , did not correctly validate that redirecturi was on the allowed list of redirect URIs for the given client registration. Fixed in: ...

CVE-2025-4143

The OAuth implementation in workers-oauth-provider that is part of MCP framework https://github.com/cloudflare/workers-mcp , did not correctly validate that redirecturi was on the allowed list of redirect URIs for the given client registration. Fixed in: ...

CVE-2025-4143

The CVE-2025-4143 entry concerns the OAuth implementation in Cloudflare’s workers-oauth-provider (MCP framework). The root cause is missing validation of redirect_uri against the client’s allowed list during authorization (the server-side code only validated the code exchange). This creates poten...

CVE-2025-4143 Missing validation of redirect_uri on authorize endpoint

The OAuth implementation in workers-oauth-provider that is part of MCP framework https://github.com/cloudflare/workers-mcp , did not correctly validate that redirecturi was on the allowed list of redirect URIs for the given client registration. Fixed in: ...

workers-oauth-provider 安全漏洞

workers-oauth-provider is a Cloudflare open source OAuth provider library for Cloudflare Workers. A security vulnerability exists in workers-oauth-provider that stems from a PKCE check being bypassed, which could lead to a failure of the protection mechanism...