Vulnerability · Published Oct 12, 2026 · Assigned by VulnCheck

CVE-2026-109371ZITADEL 3.0.0 before 4.18.0 Unauthenticated Username Change via Login V1

High 8.2

In plain English

A high-severity missing authentication in zitadel from zitadel. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).

Severity (CVSS 3.1)8.2High

Exploit odds (30 days)0.4%top 69.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
zitadel	zitadel	3.0.0 – before 4.18.0

Weakness: CWE-306 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L

References

GitHub Security Advisory (GHSA-4hgj-wm6c-q7p2) vendor-advisory
VulnCheck Advisory: ZITADEL 3.0.0 before 4.18.0 Unauthenticated Username Change via Login V1 third-party-advisory