CVE-2026-77386

Kyoo is a self-hosted media server focused on movies, series, and anime. Prior to 5.1.0, an unauthenticated attacker could initiate the OIDC login flow with an attacker-controlled redirectUrl. The login handling in auth/oidc.go stored that URL with the opaque login state, and /auth/oidc/logged/{provider} appended the provider, token, and error values before redirecting the victim's browser without validating the destination. Because the one-use token was not bound to the browser session that initiated login, an attacker who induced a victim to complete OIDC authentication could capture the token at the attacker-controlled destination and exchange it through /auth/oidc/callback/{provider} for the victim's Kyoo session. This issue is fixed in version 5.1.0.

• https://github.com/zoriya/Kyoo/commit/02ab3af8127a081295fd7bed103847173c0d7632
• https://github.com/zoriya/Kyoo/pull/1576
• https://github.com/zoriya/Kyoo/releases/tag/v5.1.0
• https://github.com/zoriya/Kyoo/security/advisories/GHSA-xhg6-v78p-xf44
• https://github.com/zoriya/Kyoo/security/advisories/GHSA-xhg6-v78p-xf44