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CVE-2026-77394

7.6 · HIGH

OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems.

Published Sep 23, 2026CWE-79EPSS 0.42%

Overview

CVE-2026-77394 is a high-severity vulnerability. It was published on September 23, 2026 and has a CVSS 3.1 base score of 7.6 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.6, rated HIGH. 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. From 5.0.6 until 7.3.0, an authenticated actor with system_set permission can store a shared screen through POST /openc3-api/screen whose BUTTON widget action is evaluated by openc3-cosmos-init/plugins/packages/openc3-vue-common/src/widgets/ButtonWidget.vue in another operator's browser session when the button is activated. The stored script runs in the COSMOS origin and can read localStorage.openc3Token, allowing theft of the victim's bearer token, account takeover, and actions with the victim's privileges. The permissive content security policy contributes to execution but is not the primary root cause. This issue is fixed in version 7.3.0.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. 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.

References

GitHubgithub.com/OpenC3/cosmos/commit/10371f8f410b9ad588f98dfa3befaaacb6587cd3GitHubgithub.com/OpenC3/cosmos/pull/3560GitHubgithub.com/OpenC3/cosmos/releases/tag/v7.3.0GitHubgithub.com/OpenC3/cosmos/security/advisories/GHSA-gvf2-2rh5-mpgfGitHubgithub.com/OpenC3/cosmos/security/advisories/GHSA-gvf2-2rh5-mpgf

How CyberStrike helps

Frequently asked questions

What is CVE-2026-77394?

CVE-2026-77394 is a high-severity vulnerability. It was published on September 23, 2026 and has a CVSS 3.1 base score of 7.6 (HIGH).

How severe is CVE-2026-77394?

This vulnerability has a CVSS 3.1 base score of 7.6, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-77394?

Check the references section for vendor advisories, patches, and mitigation guidance. 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-2026-77394?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-77394 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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