CVE-2026-109373

High

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.

SeverityHigh

CVSS8.1

Exploit probability—

ProductZitadel

PublishedOct 12, 2026

First seenOct 12, 2026

Weakness typeCWE-441CWE-441

How to fix

Update

zitadel zitadel4.19.2 or later

Vendor advisories

github.com/zitadel/zitadel/security/advisories/GHSA-jh92-5mrj-p2w2

Affected products

Product	Affected versions	Fixed in
zitadel zitadel	3.0.0 ≤ v < 4.19.2	4.19.2

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