CVE-2026-109373 ZITADEL 3.0.0 before 4.19.2 Account Takeover via Unsigned Login V2 Session Cookie
Attackers can take over user accounts, including administrators, by forging unsigned session cookies in the Login V2 UI.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-109373?
CVE-2026-109373 is a critical authentication bypass vulnerability in zitadel, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
ZITADEL 3.0.0 before 4.19.2 contains an authentication bypass vulnerability in the Login V2 UI that allows unauthenticated attackers to obtain other users' session tokens by forging unsigned session cookies. Attackers can guess time-ordered session IDs around a victim's sign-in and supply them with empty tokens to receive rotated tokens, taking over accounts including MFA-completed administrator sessions.
Weakness: CWE-441
Which versions are affected by CVE-2026-109373?
How do I fix CVE-2026-109373?
No fix has been published for CVE-2026-109373 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-109373 being exploited?
There is no known exploitation of CVE-2026-109373 in the wild and no public exploit code.
Sources
Also known as GHSA-ff7c-8692-c559, GHSA-jh92-5mrj-p2w2.