High severity · published Oct 12, 2026
CVE-2026-109373
ZITADEL 3.0.0 before 4.19.2 Account Takeover via Unsigned Login V2 Session Cookie
8.1
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 36% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ZI
zitadel · zitadel
3.0.0 before 4.19.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-109373
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-109373
vendor-advisory
https://github.com/zitadel/zitadel/security/advisories/GHSA-jh92-5mrj-p2w2
third-party-advisory
https://www.vulncheck.com/advisories/zitadel-3.0.0-before-4.19.2-account-takeover-via-unsigned-login-v2-session-cookie
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