Zimaos
CVE-2026-21891
CRITICAL
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Lifecycle Timeline
3DescriptionGitHub Advisory
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.
AnalysisAI
ZimaOS (fork of CasaOS) through 1.5.0 has an authentication bypass where passwords for system service accounts are not properly validated during login. Attackers can access the system using known service account names with any password. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | ZimaOS versions up to and including 1.5.0 with known system service account usernames (e.g., root, admin, service accounts). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | CVSS 9.4 (Critical). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker discovers a ZimaOS instance, logs in using a system service account name (e.g., 'root', 'admin', or a service name) with any password. The system grants full access, exposing all stored files and device configuration. |
| Remediation | Update ZimaOS immediately. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify all affected systems running versions and apply vendor patches immediately. …
Sign in for detailed remediation steps and compensating controls.
Threat intelligence, references, and detailed analysis are available after sign-in.
Share
External POC / Exploit Code
Leaving vuln.today