CVE-2025-57770: ZITADEL user enumeration vulnerability in login UI

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-22 · updated 2026-06-17
Weakness: CWE-203

Description

The open-source identity infrastructure software Zitadel allows administrators to disable the user self-registration. Versions 4.0.0 to 4.0.2, 3.0.0 to 3.3.6, and all versions prior to 2.71.15 are vulnerable to a username enumeration issue in the login interface. The login UI includes a security feature, Ignoring unknown usernames, that is intended to prevent username enumeration by returning a generic response for both valid and invalid usernames. This vulnerability allows an unauthenticated attacker to bypass this protection by submitting arbitrary userIDs to the select account page and distinguishing between valid and invalid accounts based on the system's response. For effective exploitation, an attacker needs to iterate through possible userIDs, but the impact can be limited by implementing rate limiting or similar measures. The issue has been patched in versions 4.0.3, 3.4.0, and 2.71.15.

Affected products

zitadel: before 2.71.15; from 3.0.0 before 3.4.0; from 4.0.0 before 4.0.3 — fixed in 2.71.15, 3.4.0, 4.0.3

How to fix

Upgrade to a fixed version: zitadel 2.71.15, 3.4.0, 4.0.3. Check the vendor advisory for mitigations.

References

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