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CriticalVulnerabilityCVE-2026-119128updated 29 Oct 2026, 16:20 UTC

ZITADEL login flaw lets attackers take over accounts with no sign-in method

Some user accounts in ZITADEL have no password or passkey set yet. An attacker could set the first sign-in method on such an account and then log in as that user.

Fixed in ZITADEL 4.19.5 or laterOfficial source
SeverityCriticalCVSS 9.1 of 10
Being exploited?UnclearNo reports either way yet
Fix available?YesZITADEL 4.19.5 or later · since 29 Oct 2026
How sure is this?Official sourceBacked by an official source

How the attack works simplified

  1. 1Attacker startsTargets a user with no sign-in method
  2. 2Forges cookieComputes verificationCheck from user ID and fingerprint
  3. 3Sets credentialAdds a password, passkey, or identity provider
  4. 4Logs inAttacker now signs in as the victim
  5. ResultAttacker controls the user account

What happened

ZITADEL versions 4.0.0 before 4.19.5 have an authentication bypass in the Login V2 UI. An unauthenticated attacker can compute a valid verificationCheck cookie from a user ID and browser fingerprint.

Why it is dangerous: An attacker can set a password, register a passkey, or link an identity provider to a user who has no authentication method, fully taking over that account.

Are you affected?

You are affected if you run ZITADEL 4.0.0 up to (but not including) 4.19.5 and have users who lack any authentication method.

ZITADEL 4.0.0 to before 4.19.5

What to do

  1. Upgrade ZITADEL to version 4.19.5 or later
  2. Review accounts that have no password, passkey, or linked identity provider and confirm they were not taken over
  3. Until patched, require every user to have an authentication method set up

Timeline

  1. 29 Oct 2026, 16:18 UTC
    Publicly disclosed
  2. 29 Oct 2026, 16:18 UTC
    Reported by NVD · NVD
  3. 29 Oct 2026, 16:20 UTC
    Picked up by Zero Radar

Sources 1 report, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-119128
CVSS
9.1 / 10
Disclosed
29 Oct 2026, 16:18 UTC
On Zero Radar
29 Oct 2026, 16:20 UTC (2 min after disclosure)
Last change
29 Oct 2026, 16:20 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

ZITADEL login flaw lets attackers take over accounts with no sign-in method · Zero Radar