AUGUST 4, 2026
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Case File

CVE-2026-21891

CRITICAL · CVSS 9.4 EPSS 2.17% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2026-01-08 · Last synced 2026-08-04

CyberRota Analysis

This is a critical severity vulnerability with a CVSS score of 9.4. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-21891
Severity
CRITICAL
CVSS
9.4
EPSS
2.17%

Original NVD 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.

Related CVEs

Other vulnerabilities affecting the same vendor(s)