CVE-2026-42086
4.6 · MEDIUMOpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems.
Overview
CVE-2026-42086 is a medium-severity vulnerability affecting openc3 cosmos. It was published on May 4, 2026 and has a CVSS 3.1 base score of 4.6 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 4.6, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical description
OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to version 7.0.0, the Command Sender UI uses an unsafe eval() function on array-like command parameters, which allows a user-supplied payload to execute in the browser when sending a command. This creates a self-XSS risk because an attacker can trigger their own script execution in the victim’s session, if allowed to influence the array parameter input, for example via phishing. If successful, an attacker may read or modify data in the authenticated browser context, including session tokens in local storage. This issue has been patched in version 7.0.0.
Remediation
Check the references section for vendor advisories and patches from openc3. Update cosmos 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 |
|---|---|---|---|
| openc3 | cosmos | >= 0, < 7.0.0 | Affected |
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Frequently asked questions
What is CVE-2026-42086?
CVE-2026-42086 is a medium-severity vulnerability affecting openc3 cosmos. It was published on May 4, 2026 and has a CVSS 3.1 base score of 4.6 (MEDIUM).
How severe is CVE-2026-42086?
This vulnerability has a CVSS 3.1 base score of 4.6, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2026-42086?
Check the references section for vendor advisories and patches from openc3. Update cosmos 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-2026-42086?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-42086 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.
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