CVE-2026-77394 OpenC3 COSMOS - Stored XSS

OpenC3 COSMOS 5.0.6 to 7.3.0 contains a stored XSS caused by evaluation of BUTTON widget action in shared screens, letting authenticated actors with system_set permission steal tokens and take over accounts, exploit requires system_set permission.

CVSS base score 7.6 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Required
EPSS
0.39% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Stored XSS
Impact
Client Script Exec, Privilege Escalation
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Published
23 September 2026
Updated
15 October 2026
Weakness
CWE-79

Vendor fix

Update to version 7.3.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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