CVE-2026-77386 Kyoo: OIDC login token can be redirected to an attacker-controlled URL
An attacker can redirect victims to a malicious URL during OIDC login to steal session tokens and take over accounts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-77386?
CVE-2026-77386 is a medium-severity vulnerability in zoriya Kyoo, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-601
Which versions are affected by CVE-2026-77386?
How do I fix CVE-2026-77386?
No fix has been published for CVE-2026-77386 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-77386 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77386 exists.
Sources
Also known as GHSA-xhg6-v78p-xf44.