TI-2026-53989 Aliases CVE-2026-77394 GHSA-gvf2-2rh5-mpgf

OpenC3 COSMOS: Stored, cross-user XSS via Telemetry screen BUTTON widget

HIGH 66CWE-79Published 2026-09-23 · Updated 2026-09-23

Key facts

Attack vector: Network
Privileges required: Low
User interaction: Required
Attack complexity: Low
Impact type: Cross-site scripting
Confidentiality · integrity · availability: High · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00417 36th percentileScored 2026-11-07

Fix Fixed cosmos (OpenC3): 7.3.0@openc3/vue-common (npm): 7.3.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
OpenC3	cosmos	5.0.6 to before 7.3.0	7.3.0	Patch available	CNA
—	@openc3/vue-common (npm)	5.0.6 to before 7.3.0	7.3.0	Patch available	GHSA-gvf2-2rh5-mpgf

cosmos VendorOpenC3 Affected 5.0.6 to before 7.3.0 Fixed in 7.3.0 Patch available CNA
@openc3/vue-common (npm) Vendor— Affected 5.0.6 to before 7.3.0 Fixed in 7.3.0 Patch available GHSA-gvf2-2rh5-mpgf

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:openc3:cosmos::::::::	—	—	OpenC3

cpe:2.3:a:openc3:cosmos:*:*:*:*:*:*:*:* Versions — — ·OpenC3

Remediation

Fix · CNA cosmos (OpenC3) Fixed in 7.3.0
Fix · GHSA-gvf2-2rh5-mpgf @openc3/vue-common (npm) Fixed in 7.3.0 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-77394
2026-10-03 Alias added: GHSA-gvf2-2rh5-mpgf

References

Other 5

TI-2025-20781 Weak password requirements in OpenC3 COSMOS v6.0.0 allow attackers to bypass authentication via a brute force attack. CVSS 3.1CRITICAL 9.8
TI-2025-20780 OpenC3 COSMOS before v6.0.2 was discovered to contain hardcoded credentials for the Service Account. CVSS 3.1CRITICAL 9.8
TI-2025-20779 A remote code execution (RCE) vulnerability in the Plugin Management component of OpenC3… CVSS 3.1CRITICAL 9.8
TI-2025-20778 An issue in the /script-api/scripts/ endpoint of OpenC3 COSMOS before 6.1.0 allows… CVSS 3.1CRITICAL 9.1
TI-2026-54090 Code injection in OpenC3 cosmos CVSS 3.1CRITICAL 9.9
TI-2026-30456 OpenC3 COSMOS: Administrative Actions via the Script Runner Tool CVSS 3.1CRITICAL 9.6

See all 18 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences