CVE-2026-56666 ZITADEL: Auto-linking by email: IdP-side email verification is not checked
Attackers can take over victim accounts by linking permissive external IdP profiles to local accounts without proper email verification checks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-56666?
CVE-2026-56666 is a medium-severity authentication bypass vulnerability in zitadel, published on 10 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
ZITADEL is an open source identity management platform. Prior to 4.15.3, ZITADEL's external identity provider handler checks that the local user's email is verified but does not verify that the external IdP confirmed ownership of the same email before auto-linking by email, allowing a permissive provider account with a victim email address to be linked to the victim's local account. This issue is fixed in version 4.15.3.
Weakness: CWE-287
Which versions are affected by CVE-2026-56666?
3 open source packages ship an affected version, including github.com/zitadel/zitadel.
| Package | Affected | Fixed in |
|---|---|---|
github.com/zitadel/zitadel Go | All versions | None |
github.com/zitadel/zitadel Go | All versions | 4.15.3 |
github.com/zitadel/zitadel Go | All versions | 4.15.3 |
How do I fix CVE-2026-56666?
Upgrade github.com/zitadel/zitadel to 4.15.3 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-56666 being exploited?
There is no known exploitation of CVE-2026-56666 in the wild and no public exploit code.
Sources
Also known as GHSA-992q-9gwp-7r79, GO-2026-6470.