Zitadel allows brute-forcing authentication factors

### Summary A vulnerability in Zitadel allowed brute-force attack on OTP, TOTP and password allowing to impersonate the attacked user. ### Impact An attacker can perform an online brute-force attack on OTP, TOTP, and passwords. While Zitadel allows preventing online brute force attacks in scenarios like TOTP, Email OTP, or passwords using a lockout mechanism. The mechanism is not enabled by default and can cause a denial of service for the corresponding user if enabled. Additionally, the mitigation strategies were not fully implemented in the more recent resource-based APIs. ### Affected Versions All versions within the following ranges, including release candidates (RCs), are affected: - **4.x**: `4.0.0` to `4.4.0` (including RC versions) - **3.x**: `3.0.0` to `3.4.2` (including RC versions) - **2.x**: `v2.0.0` to `2.71.17` ### Patches The vulnerability has been addressed in the latest releases. The patch resolves the issue by enforcing the lockout policy on all OTP, TOTP and password checks. Additionally a “tar pit” has been introduced to slow down brute-force attacks by default. Zitadel responses will be delayed by t seconds, where t increases over the number of failed attempts within a given timeframe. 4.x: Upgrade to >=[4.6.0](https://github.com/zitadel/zitadel/releases/tag/v4.6.0) 3.x: Update to >=[3.4.3](https://github.com/zitadel/zitadel/releases/tag/v3.4.3) 2.x: Update to >=[2.71.18](https://github.com/zitadel/zitadel/releases/tag/v2.71.18) ### Workarounds The recommended solution is to update Zitadel to a patched version. The problem might be mitigated by enabling the optional logout policy ("Password maximum attempts") or by implementing more strict rate limits. ### Questions If you have any questions or comments about this advisory, please email us at [[email protected]](mailto:[email protected]) ### Credits This vulnerability was found by [zentrust partners GmbH](https://zentrust.partners) 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.

Source published

29 Oct 2025 22:21:05 UTC

Source modified

5 Nov 2025 22:13:38 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Publisher rating · HIGH