🛡️ CVE-2026-21891 — zimaos

🔴 CVSS 9.4 — Critical ⚠️ Exploit Public CWE-287 NVD
9.4
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability low.

Weakness class

CVE-2026-21891 is classified as CWE-287: Improper Authentication. The identity of the caller is not established correctly, so an attacker can act as another user.

Affected software

CVE-2026-21891 is recorded against 1 package.

  • zimaos (fixed in 1.5.0)

Timeline and source

Published on 8 January 2026 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. Record sourced from NVD.

References

github.com
github.com

Details

Severity CRITICAL
CVSS Score 9.4
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
CWE CWE-287
Public Exploit ⚠️ Yes
Source NVD
Published 2026-01-08
Updated 2026-08-11
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
zimaos — 1.5.0

Similar Threats

Exploit Protection

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