Auth bypass in Zitadel
CVE-2026-105207
ZITADEL 3.0.0 through 3.4.15 and 4.0.0 before 4.17.3 creates links between user accounts and external identity providers without verifying a primary factor or the caller's permission, including on identify-only Login V2 sessions and via the User Service V2 AddIDPLink endpoint. An unauthenticated attacker knowing a victim's login name can bind their own external IdP identity to the victim's account and then sign in as the victim.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/zitadel/zitadel/security/advisories/GHSA-g8gj-gq47-xgf4 (vendor-advisory)
- www.vulncheck.com/advisories/zitadel-before-4.17.3-account-takeover-via-externa… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-105207?
- CVE-2026-105207 is a critical-severity vulnerability in Zitadel, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-10-04.
- How severe is CVE-2026-105207?
- Critical severity. CVSS v3 base score is 9.8 out of 10.