Vulnerability · Published Jan 8, 2026 · Assigned by GitHub_M
CVE-2026-21891ZimaOS has Authentication Bypass via System-Level Username
Critical 9.4
In plain English
A critical-severity improper authentication in ZimaOS from IceWhaleTech. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 2.3% (higher than 83% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei.
Official description
ZimaOS is a fork of CasaOS, an operating system for Zima devices and x86-64 systems with UEFI. In versions up to and including 1.5.0, the application checks the validity of the username but appears to skip, misinterpret, or incorrectly validate the password when the provided username matches a known system service account. The application's login function fails to properly handle the password validation result for these users, effectively granting authenticated access to anyone who knows one of these common usernames and provides any password. As of time of publication, no known patched versions are available.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| IceWhaleTech | ZimaOS | <= 1.5.0 |
Weakness: CWE-287 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
References
- https://github.com/IceWhaleTech/ZimaOS/security/advisories/GHSA-xj93-qw9p-jxq4 x_refsource_CONFIRM