CVE-2025-31124: Zitadel allows User Enumeration by loginname attribute normalization

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-03-31 · updated 2026-06-17
Weakness: CWE-200

Description

Zitadel is open-source identity infrastructure software. ZITADEL administrators can enable a setting called "Ignoring unknown usernames" which helps mitigate attacks that try to guess/enumerate usernames. If enabled, ZITADEL will show the password prompt even if the user doesn't exist and report "Username or Password invalid". While the setting was correctly respected during the login flow, the user's username was normalized leading to a disclosure of the user's existence. This vulnerability is fixed in 2.71.6, 2.70.8, 2.69.9, 2.68.9, 2.67.13, 2.66.16, 2.65.7, 2.64.6, and 2.63.9.

Affected products

zitadel: before 2.63.9; from 2.64.0 before 2.64.6; from 2.65.0 before 2.65.7; from 2.66.0 before 2.66.16; from 2.67.0 before 2.67.13; from 2.68.0 before 2.68.9 — fixed in 2.63.9, 2.64.6, 2.65.7, 2.66.16, 2.67.13, 2.68.9

How to fix

Upgrade to a fixed version: zitadel 2.63.9, 2.64.6, 2.65.7, 2.66.16. Check the vendor advisory for mitigations.

References

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