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Vulnerabilities

Vulnerability · CVE-2026-109371

ZITADEL 3.0.0 before 4.18.0 Unauthenticated Username Change via Login V1

Published Oct 12, 2026 · catalog updated Oct 15, 2026 · ZITADEL 3.0.0 before 4.18.0

Check if you run it

No confirmed exploitation is on record for CVE-2026-109371. EPSS is 0.36%. Act only if a listed version of ZITADEL 3.0.0 before 4.18.0 is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (ZITADEL 3.0.0 before 4.18.0).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.36%
Remediation
Advisory link
Affected products
vendor zitadel zitadel

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor zitadel zitadelversion unspecified

How to fix CVE-2026-109371

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-109371. EPSS is 0.36%. Act only if a listed version of ZITADEL 3.0.0 before 4.18.0 is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-306: Missing Authentication for Critical Function. EPSS 0.36%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 12, 2026 · NIST NVD

    Detected

    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.

  2. Oct 15, 2026 · NIST NVD

    Updated

    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.

Sources

  • CIRCL Vulnerability LookupVulnerability recordCVE-2026-109371

    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 po

    vulnerability.circl.lu
  • CVE.orgVulnerability recordCVE-2026-109371

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-109371

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-109371

    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 po

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.