---
id: CVE-2026-109373
title: >-
  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
summary: >-
  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-orde…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-441
published: '2026-10-12'
updated: '2026-10-12'
sourceUpdated: '2026-10-12T17:17:35.230'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109373'
references:
  - url: 'https://github.com/zitadel/zitadel/security/advisories/GHSA-jh92-5mrj-p2w2'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/zitadel-3.0.0-before-4.19.2-account-takeover-via-unsigned-login-v2-session-cookie
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-10-12T18:00:08.217Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.