GHSA-f4cf-9rvr-2rcx Zitadel Discloses the Total Number of Instance Users

• Go github.com/zitadel/zitadel: >= 4.0.0-rc.1, < 4.7.2 → fixed in 4.7.2 • Go github.com/zitadel/zitadel: >= 2.44.0, < 3.4.5 → fixed in 3.4.5 • Go github.com/zitadel/zitadel: < 1.80.0-v2.20.0.20251210121356-826039c6208f → fixed in 1.80.0-v2.20.0.20251210121356-826039c6208f

Summary Zitadel's User Service discloses the total number of instance users to unauthorized users. Impact The ZITADEL User Service exposes the total number of users within an instance to any authenticated user, regardless of their specific permissions. While this does not leak individual user data or PII, disclosing the total user count via the `totalResult` field constitutes an information disclosure vulnerability that may be sensitive in certain contexts. Affected Versions Systems running one of the following version are affected: • 4.x: `4.0.0-rc.1` through `4.7.1` • 3.x: `3.0.0-rc.1` through `3.4.4` • 2.x: `2.44.0` through `2.71.19` Patches The vulnerability has been addressed in the latest release. The patch resolves the issue and returns the `totalResult` value corresponding to the number of instance users for whom the querying user has read permission. • 4.x: Upgrade to >= 4.7.2 • 3.x: Update to >= 3.4.5 • 2.x: Update to >= 3.4.5 (or checkout the workarounds section) Workarounds The recommended solution is to update Zitadel to a patched version. If a version upgrade is not possible, you can enable the `permissionCheckV2` feature on your instance. Questions If you have any questions or comments about this advisory, please email us at [email protected] Credits This vulnerability was found by zentrust partners GmbH during a scheduled penetration test. Thank you to the analysts Martin Tschirsich, Joud Zakharia, Christopher Baumann. The full report will be made public after the complete review.