{"id":"CVE-2026-109371","published":"2026-10-12T17:17:34.547","lastModified":"2026-10-15T03:17:10.390","description":"ZITADEL 3.0.0 before 4.18.0 contains a missing authentication vulnerability in the hosted Login V1 UI, where the change-username handler acts on the account bound to a login flow before any factor is verified. Unauthenticated attackers can submit a victim's login name and then post a new username to rename any active human user, including administrators, locking them out.","cvssScore":8.2,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L","cwes":["CWE-306"],"vendors":[],"products":[],"references":[{"url":"https://github.com/zitadel/zitadel/security/advisories/GHSA-4hgj-wm6c-q7p2","tags":[]},{"url":"https://www.vulncheck.com/advisories/zitadel-3.0.0-before-4.18.0-unauthenticated-username-change-via-login-v1","tags":[]}],"exploitRefs":[{"url":"https://github.com/zitadel/zitadel/security/advisories/GHSA-4hgj-wm6c-q7p2","tags":[]}],"hasPoc":true,"ai":null}