{"cve":"CVE-2026-77394","nvd":{"published":"2026-09-23T19:19:15.343","modified":"2026-09-23T20:17:15.660","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N","score":7.6},"cwes":["CWE-79"],"references":["https://github.com/OpenC3/cosmos/commit/10371f8f410b9ad588f98dfa3befaaacb6587cd3","https://github.com/OpenC3/cosmos/pull/3560","https://github.com/OpenC3/cosmos/releases/tag/v7.3.0","https://github.com/OpenC3/cosmos/security/advisories/GHSA-gvf2-2rh5-mpgf","https://github.com/OpenC3/cosmos/security/advisories/GHSA-gvf2-2rh5-mpgf"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-77394","score":0.00417,"percentile":0.36099,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-gvf2-2rh5-mpgf","url":"https://osv.dev/vulnerability/GHSA-gvf2-2rh5-mpgf","summary":"OpenC3 COSMOS: Stored, cross-user XSS via Telemetry screen BUTTON widget","modified":"2026-09-23T21:45:07.938130889Z","packages":[{"ecosystem":"npm","name":"@openc3/vue-common","purl":"pkg:npm/%40openc3/vue-common","ranges":[">=5.0.6 <7.3.0"],"fixed":["7.3.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}