← Vulnerability feed

Vulnerability record · CVE-2026-77394 · published 23 September 2026

CVE-2026-77394: Cross-site scripting vulnerability

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.

7.6 CVSS 3.1 High EPSS 0.39% · top 69.6% CWE-79 · Cross-site scripting Deferred
7.6CVSS 3.1 base score
0.39%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
5References
23 Sep 2026Last modified by NVD

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:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

References

LinkTags
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

Track CVE-2026-77394 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

6.1CVE-2026-42897Microsoft Exchange Server XSS enables spoofingMicrosoft Exchange Server and Exchange Server Subscription Edition fail to neutralize input during web page generation, a cross-site scripting flaw (…KEVEPSS 0.52%analysed6.1CVE-2025-48700Zimbra Classic UI stored XSS via crafted email HTMLZimbra Collaboration Suite Classic UI fails to properly sanitize HTML content in email messages, allowing crafted tag structures and attribute values…KEVEPSS 1.7%analysed6.1CVE-2025-66376Zimbra Collaboration Classic UI stored XSS via CSS @import in emailZimbra Collaboration Suite 10 before 10.0.18 and 10.1 before 10.1.13 allows stored cross-site scripting in the Classic UI through CSS @import directi…KEVEPSS 20%analysed6.1CVE-2025-68461Roundcube Webmail XSS via SVG animate tagRoundcube Webmail before 1.5.12 and 1.6 before 1.6.12 is vulnerable to cross-site scripting through the animate tag in an SVG document. Because the f…KEVEPSS 27%analysed10.0CVE-2026-22769Dell RecoverPoint for Virtual Machines hardcoded credential flawDell RecoverPoint for Virtual Machines versions prior to 6.0.3.1 HF1 contain a hardcoded credential vulnerability (CWE-798). An unauthenticated remot…KEVEPSS 13%analysed7.1CVE-2025-14611Gladinet CentreStack and Triofox hardcoded AES key enables file inclusionCentreStack and Triofox before 16.12.10420.56791 use hardcoded values in their AES cryptoscheme, weakening protection for publicly exposed endpoints.…KEVEPSS 53%analysed5.4CVE-2021-26829OpenPLC ScadaBR stored XSS via system_settings.shtmOpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored cross-site scripting through system_settings.shtm. Because the inj…KEVEPSS 48%analysed5.4CVE-2025-27915Zimbra Classic Web Client stored XSS via ICS file HTMLZimbra Collaboration Suite 9.0, 10.0 and 10.1 fail to sanitize HTML content in ICS files in the Classic Web Client. A malicious ICS entry embedded in…KEVEPSS 4.0%analysed

Source: NIST National Vulnerability Database (record CVE-2026-77394), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.