CVE-2026-77394

HIGHPre-NVD 7.67.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (30th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
7.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.6Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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 v3
7.6
EG Score
7.6HIGHmedium confidence
EG Risk
50
EG Risk 50/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity76% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
30th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 23, 2026

Last Modified

September 23, 2026

Advisory Details (4)

Auto-updated Sep 23, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

v7.3.0

Patch available: OpenC3/cosmos v7.3.0

https://github.com/OpenC3/cosmos/releases/tag/v7.3.0
github_commit

commit 10371f8f410b (OpenC3/cosmos)

Fix landed in OpenC3/cosmos commit 10371f8f410b — awaiting tagged release

https://github.com/OpenC3/cosmos/commit/10371f8f410b9ad588f98dfa3befaaacb6587cd3
github_pr

Make button eval safe

Fix merged in OpenC3/cosmos PR #3560 on 2026-07-14 — awaiting tagged release

https://github.com/OpenC3/cosmos/pull/3560
github Patch Available🟡 PoC Available

Stored, cross-user XSS via Telemetry screen BUTTON widget · Advisory · OpenC3/cosmos · GitHub

https://github.com/OpenC3/cosmos/security/advisories/GHSA-gvf2-2rh5-mpgf

Vendor Advisories for CVE-2026-77394(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
@openc3/vue-common—7.3.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 22× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-03 16:42 UTCEG score recompute
  2. 2026-10-03 14:26 UTCEPSS rescore
  3. 2026-10-03 04:56 UTCEG score recompute
  4. 2026-10-02 05:23 UTCEG score recompute
  5. 2026-10-01 19:50 UTCEPSS rescore
  6. 2026-09-30 17:59 UTCEG score recompute
  7. 2026-09-29 18:16 UTCEG score recompute
  8. 2026-09-29 15:24 UTCEPSS rescore
  9. 2026-09-29 06:00 UTCEG score recompute
  10. 2026-09-27 18:39 UTCEG score recompute
  11. 2026-09-27 13:48 UTCEPSS rescore
  12. 2026-09-26 19:05 UTCEG score recompute
  13. 2026-09-26 15:59 UTCEPSS rescore
  14. 2026-09-26 07:16 UTCEG score recompute
  15. 2026-09-26 00:28 UTCEPSS rescore
  16. 2026-09-24 19:56 UTCEG score recompute
  17. 2026-09-24 14:04 UTCEPSS rescore
  18. 2026-09-23 20:22 UTCEG score recompute
  19. 2026-09-23 19:39 UTCEG score recompute
  20. 2026-09-23 19:26 UTCEG score recompute
  21. 2026-09-23 18:59 UTCEG score recompute
  22. 2026-09-23 18:59 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-77394?
CVE-2026-77394 is a high vulnerability published on September 23, 2026. 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…
When was CVE-2026-77394 disclosed?
CVE-2026-77394 was first published on September 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77394 actively exploited?
CVE-2026-77394 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (30th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-77394?
CVE-2026-77394 has a CVSS base score of 7.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-77394?
A fix for CVE-2026-77394 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-77394 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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