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GHSA-pvm5-9frx-264r
No affected components available
Summary
A user enumeration vulnerability has been discovered in Zitadel's login interfaces. An unauthenticated attacker can exploit this flaw to confirm the existence of valid user accounts by iterating through usernames and userIDs.
Impact
The login UIs (in version 1 and 2) provide the possibility to request a password reset, where an email will be sent to the user with a link to a verification endpoint. By submitting arbitrary userIDs to these endpoints, an attacker can differentiate between valid and invalid accounts based on the system's response.
For an effective exploit the attacker needs to iterate through the potential set of userIDs. The impact can be limited by implementing rate limiting or similar measures to limit enumeration of userIDs.
Additionally, Zitadel includes a security feature "Ignoring unknown usernames", designed to prevent username enumeration attacks by presenting a generic response for both valid and invalid usernames on the login page. The login UI V2 did not handle the setting correctly and would allow attackers to enumerate through usernames to check their existence.
Affected Versions
All versions within the following ranges, including release candidates (RCs), are affected:
- v4.x:
4.0.0through4.9.0 - 3.x:
3.0.0through3.4.5 - 2.x:
2.0.0through2.71.19
Patches
The vulnerability has been addressed in the latest releases. The patch resolves the issue by returning a generic error message, which does not indicate it the user exists.
4.x: Upgrade to >=4.9.1 3.x: Update to >=3.4.6 2.x: Update to >=3.4.6
Workarounds
The recommended solution is to update ZITADEL to a patched version. You can limit the impact by implementing rate limiting or similar measures to limit enumeration of userIDs.
There is no workaround for the "Ignoring unknown usernames" issue in login V2. Please upgrade to a patched version, if you rely on this feature.
Questions
If you have any questions or comments about this advisory, please email us at security@zitadel.com
Credits
Thanks to Niklas Kunz from Seamly for reporting this vulnerability from their pentest.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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