FastMCP: Missing Consent Verification in OAuth Proxy Callback Facilitates Confused Deputy Vulnerabilities

SummaryWhile testing the GitHubProvider OAuth integration, which allows authentication to a FastMCP MCP server via a FastMCP OAuthProxy using GitHub OAuth, it was discovered that the FastMCP OAuthProxy does not properly validate the user's consent upon receiving the authorization code from GitHub...

PYSEC-2026-2476 FastMCP: Missing Consent Verification in OAuth Proxy Callback Facilitates Confused Deputy Vulnerabilities

Summary While testing the GitHubProvider OAuth integration, which allows authentication to a FastMCP MCP server via a FastMCP OAuthProxy using GitHub OAuth, it was discovered that the FastMCP OAuthProxy does not properly validate the user's consent upon receiving the authorization code from GitHu...

CVE-2026-55672 ZITADEL: Missing client_id binding in OIDC authorization code exchange and refresh token flows (RFC 6749 Section 4.1.3 violation)

ZITADEL is an open source identity management platform. Prior to 3.4.12 and 4.15.2, ZITADEL's OAuth2 and OIDC CodeExchange, RefreshToken, and device token flows fail to verify that the requesting client matches the client that initiated the authorization flow, allowing intercepted grants or refre...

CVE-2026-55672

Summary (concrete details) : The CVE concerns Zitadel, an open-source identity management platform. The vulnerability occurs in the OAuth2/OIDC CodeExchange and RefreshToken flows (and related device token flow) where verification that the requesting client matches the originally authorized clien...

Time-of-check Time-of-use (TOCTOU) Race Condition

Overview @better-auth/oauth-provider is an An oauth provider plugin for Better Auth Affected versions of this package are vulnerable to Time-of-check Time-of-use TOCTOU Race Condition through a race condition in the authorizationcode grant handler. An attacker can obtain multiple valid access,...

NPM: @better-auth/oauth-provider's OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive

NPM: @better-auth/oauth-provider's OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive vulnerability discovered by ? in WordPress Npm better-auth versions 1.6.11...

@better-auth/oauth-provider's OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive

Am I affected? Users are affected if all of the following are true: - Their project depends on @better-auth/oauth-provider at a version = 1.6.0, = 1.4.8-beta.7, 1.6.0, or enables the legacy oidc-provider or mcp plugins from better-auth/plugins. - Their application exposes /api/auth/oauth2/token o...

Time-of-check Time-of-use (TOCTOU) Race Condition

Overview better-auth is a The most comprehensive authentication library for TypeScript. Affected versions of this package are vulnerable to Time-of-check Time-of-use TOCTOU Race Condition through a race condition in the authorizationcode grant handler. An attacker can obtain multiple valid access...

GHSA-7W99-5WM4-3G79 @better-auth/oauth-provider's OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive

Am I affected? Users are affected if all of the following are true: - Their project depends on @better-auth/oauth-provider at a version = 1.6.0, = 1.4.8-beta.7, 1.6.0, or enables the legacy oidc-provider or mcp plugins from better-auth/plugins. - Their application exposes /api/auth/oauth2/token o...

PT-2026-56302

Name of the Vulnerable Software and Affected Versions @better-auth/oauth-provider versions 1.6.0 through 1.6.10 better-auth versions 1.4.8-beta.7 through 1.6.10 Description The POST /oauth2/token endpoint for the authorization code grant redeems a single-use authorization code using a non-atomic...

EUVD-2026-41941

Leantime contains an OIDC login CSRF vulnerability in the verifyState method that unconditionally returns true without validating state parameters. Attackers can craft malicious callback URLs with attacker-controlled authorization codes to perform session fixation, logging victims in as the...

Replay Attack

Overview Affected versions of this package are vulnerable to Replay Attack due to improper enforcement of OAuth2 authorization code expiry and single-use requirements in the authorization code process. An attacker can gain unauthorized access by reusing valid authorization codes during the token...

Replay Attack

Overview Affected versions of this package are vulnerable to Replay Attack due to improper enforcement of OAuth2 authorization code expiry and single-use requirements in the authorization code process. An attacker can gain unauthorized access by reusing valid authorization codes during the token...

Replay Attack

Overview Affected versions of this package are vulnerable to Replay Attack due to improper enforcement of OAuth2 authorization code expiry and single-use requirements in the authorization code process. An attacker can gain unauthorized access by reusing valid authorization codes during the token...

GHSA-5V69-G2M3-3HQ3 Gitea OAuth2 authorization codes can be reused after expiry

Gitea versions before 1.25.5 do not consistently enforce OAuth2 authorization code expiry and single-use behavior during token exchange...

Gitea OAuth2 authorization codes can be reused after expiry

Gitea versions before 1.25.5 do not consistently enforce OAuth2 authorization code expiry and single-use behavior during token exchange...

CVE-2026-26232

Gitea versions before 1.25.5 do not consistently enforce OAuth2 authorization code expiry and single-use behavior during token exchange...

CVE-2026-26232 Gitea OAuth2 authorization codes lack expiry and reuse enforcement

Gitea versions before 1.25.5 do not consistently enforce OAuth2 authorization code expiry and single-use behavior during token exchange...

CVE-2026-26232 Gitea OAuth2 authorization codes lack expiry and reuse enforcement

Gitea versions before 1.25.5 do not consistently enforce OAuth2 authorization code expiry and single-use behavior during token exchange...

CVE-2026-26232 Gitea OAuth2 authorization codes lack expiry and reuse enforcement

Gitea versions before 1.25.5 do not consistently enforce OAuth2 authorization code expiry and single-use behavior during token exchange...