CVE-2026-21891
9.4 · CRITICALOverview
CVE-2026-21891 is a critical-severity vulnerability affecting zimaspace zimaos. It was published on January 8, 2026 and has a CVSS 3.1 base score of 9.4 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.4, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from zimaspace. Update zimaos to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| zimaspace | zimaos | 0 | Affected |
Frequently Asked Questions
What is CVE-2026-21891?
CVE-2026-21891 is a critical-severity vulnerability affecting zimaspace zimaos. It was published on January 8, 2026 and has a CVSS 3.1 base score of 9.4 (CRITICAL).
How severe is CVE-2026-21891?
This vulnerability has a CVSS 3.1 base score of 9.4, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-21891?
Check the references section for vendor advisories and patches from zimaspace. Update zimaos to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-21891?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-21891 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
AI-driven PR review catches vulnerable dependencies before they ship.
Browser-based exploitation validates findings with real proof-of-concept.
Related CRITICAL CVEs from 2026
View all →A command injection vulnerability in the execute_command function of terminal-controller-mcp 0.1.7 a
n8n is an open source workflow automation platform. Versions starting with 1.65.0 and below 1.121.0
Fastjson before 1.2.48 mishandles autoType because, when an @type key is in a JSON document, and the
This vulnerability allows authenticated attackers to execute commands via the hostname of the device
Remote Code Execution vulnerability that allows unauthenticated attackers to inject arbitrary comman
XWiki Full Calendar Macro displays objects from the wiki on the calendar. Prior to version 2.4.5, us
Successful exploitation of the SQL injection vulnerability could allow an unauthenticated remote att
A static password reset token in the password reset function of DDSN Interactive Acora CMS v10.7.1 a
Affected devices do not properly enforce user authentication on specific API endpoints. This could f
Sandbox escape in the Messaging System component. This vulnerability was fixed in Firefox 147 and Th
OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or mor
Enclave is a secure JavaScript sandbox designed for safe AI agent code execution. Prior to 2.7.0, th