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...

PT-2026-29421

Name of the Vulnerable Software and Affected Versions: FastMCP versions prior to 3.2.0 Description: FastMCP is susceptible to a Confused Deputy issue within its GitHubProvider OAuth integration. The OAuthProxy component fails to properly validate user consent when receiving authorization codes fr...

CVE-2026-33757 OpenBao lacks user confirmation for OIDC direct callback mode

OpenBao is an open source identity-based secrets management system. Prior to version 2.5.2, OpenBao does not prompt for user confirmation when logging in via JWT/OIDC and a role with callbackmode set to direct. This allows an attacker to start an authentication request and perform "remote phishin...

OpenBao lacks user confirmation for OIDC direct callback mode

Impact OpenBao does not prompt for user confirmation when logging in via JWT/OIDC and a role with callbackmode set to direct. This allows an attacker to start an authentication request and perform "remote phishing" by having the victim visit the URL and automatically log-in to the session of the...

CVE-2026-32245

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their...

SUSE CVE-2026-32245

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their...

CVE-2026-28498 Authlib: Fail-Open Cryptographic Verification in OIDC Hash Binding

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a library-level vulnerability was identified in the Authlib Python library concerning the validation of OpenID Connect OIDC ID Tokens. Specifically, the internal hash verification logic verifyhash...

CVE-2026-32245

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their...

CVE-2026-32245 Tinyauth's OIDC authorization codes are not bound to client on token exchange

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their...

CVE-2026-32245

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their...

CVE-2026-32245

CVE-2026-32245 concerns Tinyauth, an authentication/authorization server. The issue, present before 5.0.3, is that the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client to which the code was issued. A malicious OIDC client operator can exchang...

CVE-2026-32245 Tinyauth's OIDC authorization codes are not bound to client on token exchange

Tinyauth is an authentication and authorization server. Prior to 5.0.3, the OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their...

CVE-2026-32235

Backstage is an open framework for building developer portals. Prior to 0.27.1, the experimental OIDC provider in @backstage/plugin-auth-backend is vulnerable to a redirect URI allowlist bypass. Instances that have enabled experimental Dynamic Client Registration or Client ID Metadata Documents a...

GHSA-3Q28-QJRV-QR39 Tinyauth vulnerable to TOTP/2FA bypass via OIDC authorize endpoint

Summary The OIDC authorization endpoint allows users with a TOTP-pending session password verified, TOTP not yet completed to obtain authorization codes. An attacker who knows a user's password but not their TOTP secret can obtain valid OIDC tokens, completely bypassing the second factor. Details...

Tinyauth vulnerable to TOTP/2FA bypass via OIDC authorize endpoint

Summary The OIDC authorization endpoint allows users with a TOTP-pending session password verified, TOTP not yet completed to obtain authorization codes. An attacker who knows a user's password but not their TOTP secret can obtain valid OIDC tokens, completely bypassing the second factor. Details...

GHSA-XG2Q-62G2-CVCM Tinyauth's OIDC authorization codes are not bound to client on token exchange

Summary The OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their own client credentials, obtaining tokens for users who never...

GHSA-WQVH-63MV-9W92 @backstage/plugin-auth-backend: OAuth redirect URI allowlist bypass

Impact The experimental OIDC provider in @backstage/plugin-auth-backend is vulnerable to a redirect URI allowlist bypass. Instances that have enabled experimental Dynamic Client Registration or Client ID Metadata Documents and configured allowedRedirectUriPatterns are affected. A specially crafte...

PT-2026-25055

Name of the Vulnerable Software and Affected Versions Tinyauth versions prior to 5.0.3 Description Tinyauth is an authentication and authorization server. The OIDC token endpoint does not verify that the client exchanging an authorization code is the same client to which the code was originally...

GO-2026-4656 Pocket ID: OIDC authorization code validation uses AND instead of OR, allowing cross-client token exchange in github.com/pocket-id/pocket-id/backend

Pocket ID: OIDC authorization code validation uses AND instead of OR, allowing cross-client token exchange in github.com/pocket-id/pocket-id/backend...

CVE-2026-28512

Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to your services. From 2.0.0 to before 2.4.0, a flaw in callback URL validation allowed crafted redirecturi values containing URL userinfo @ to bypass legitimate callback pattern checks. If an attacker can trick a...