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TI-2026-17591 Aliases CVE-2026-21891

ZimaOS has Authentication Bypass via System-Level Username

Priority HIGH 82CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-287.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.02316 83rd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
IceWhaleTechZimaOSup to 1.5.0—No fix listedCNA
  • ZimaOS VendorIceWhaleTech Affected up to 1.5.0 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:zimaspace:zimaos:*:*:*:*:*:*:*:*up to 1.5.0VulnerableZimaspace
  • cpe:2.3:o:zimaspace:zimaos:*:*:*:*:*:*:*:* Versions up to 1.5.0 Vulnerable ·Zimaspace

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-21891

References

Exploit 1

  • TI-2024-16284 CasaOS Improper Restriction of Excessive Authentication Attempts vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2024-16282 CasaOS-UserService allows unauthorized access to any file CVSS 3.1CRITICAL 9.8
  • TI-2024-32947 ZimaOS vulnerable to Directory Listing via Parameter Manipulation CVSS 3.1HIGH 7.5
  • TI-2024-32626 ZimaOS Arbitrary File Read via Parameter Manipulation CVSS 3.1HIGH 7.5
  • TI-2023-19077 CasaOS Command Injection vulnerability CVSS 3.1HIGH 8.8
  • TI-2026-22712 ZimaOS: Arbitrary Deletion of Internal System Files via API Path Manipulation CVSS 3.1HIGH 8.6
See all 20 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences