CVE-2026-77602 OpenC3 CVE debrief

Who should care

Defenders responsible for OpenC3 COSMOS deployments, especially those with authenticated non-administrator users, should assess exposure and prioritize verification and remediation efforts.

Why it matters

CVE-2026-77602 is a critical vulnerability in OpenC3 COSMOS that allows authenticated non-administrator users to write and execute content with elevated privileges, potentially leading to code execution, unauthorized access, and data breaches. Defenders should prioritize verifying exposure, restricting user access, and monitoring for suspicious activity.

• Potential code execution with elevated privileges
• Possible unauthorized access to internal credentials and data
• Required verification of OpenC3 COSMOS version and user access controls
• Necessary monitoring for suspicious activity in cmd-tlm-api, decom microservices, and Script Runner

Technical summary

CVE-2026-77602 is a critical vulnerability in OpenC3 COSMOS that allows authenticated non-administrator users to write content under targets_modified/ that is later executed by multiple configuration paths below the intended code-execution privilege tier. The issue is fixed in version 7.3.0. This vulnerability could lead to code execution, unauthorized access, and data breaches. Defenders should prioritize verifying exposure in OpenC3 COSMOS deployments, especially for authenticated non-administrator users, and assess the effectiveness of existing compensating controls. The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions.

Defensive priority

Defenders should prioritize verifying exposure in OpenC3 COSMOS deployments, especially for authenticated non-administrator users, and assess the effectiveness of existing compensating controls.

Recommended defensive actions

• Verify OpenC3 COSMOS version and upgrade to 7.3.0 if necessary
• Restrict access to authenticated non-administrator users
• Monitor for suspicious activity in cmd-tlm-api, decom microservices, and Script Runner
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. However, the corpus does not establish specific exploitation instances or victim organizations.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.