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Vulnerabilities

Vulnerability · CVE-2026-21891

zimaspace zimaos Improper Authentication

Published Mar 7, 2026 · catalog updated Mar 7, 2026 · zimaspace zimaos Improper Authentication

Patch now

CVE-2026-21891 is in the CISA known-exploited catalog. Confirm zimaspace zimaos Improper Authentication against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (zimaspace zimaos Improper Authentication).
Severity
Unknown—
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
2.32%
Remediation
Remediation guidance
Affected products
stated zimaos · vendor zimaspace zimaos

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 versio

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • stated zimaos<= 1.5.0
  • vendor zimaspace zimaosversion unspecified

How to fix CVE-2026-21891

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2026-21891 is in the CISA known-exploited catalog. Confirm zimaspace zimaos Improper Authentication against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with <= 1.5.0. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

What should an analyst verify?

No weakness class is stored. EPSS 2.32%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 7, 2026 · VulnCheck KEV

    Detected

    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 vali

  2. Mar 7, 2026 · CISA KEV

    Known exploited

    Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Sources

  • CVE.orgVulnerability recordCVE-2026-21891

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-21891

    30-day exploitation probability 2.3%

    first.org
  • VulnCheck KEVConfirmed exploitationCVE-2026-21891

    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 user

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.