CVE-2026-21891
CRITICALCVSS v3
9.4
CRITICAL
EPSS Score
13.6%
exploit probability
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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
Technical Details
- CVSS v3 Vector
- 3.1
- Published
- 1/8/2026
- Last Modified
- 1/12/2026
Frequently Asked Questions
What is CVE-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 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
Is CVE-2026-21891 actively exploited?
Active exploitation of CVE-2026-21891 has not been confirmed. The EPSS score is 13.6%, indicating the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2026-21891?
CVE-2026-21891 has a CVSS v3 base score of 9.4 (CRITICAL severity), with vector string 3.1.
Is CVE-2026-21891 affecting your environment?
Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.