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.
CVE-2026-77394
“—” beside the score: it is equal to the CVSS score beside it.
Score 7.6 from GitHub Security Advisory (severity: HIGH) published 2026-09-23. A secondary CVSS source baseline 7.6; sources differ by 0.0.
Also known asEUVD-2026-85564 (ENISA EUVD) · GHSA-gvf2-2rh5-mpgf (GitHub Security Advisories)Source: ENISA EUVD
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
A fix is available — apply it.
- CVSS v3
- 7.6
- EG Score
- 7.6HIGHmedium confidence
- EG Risk
- 50EG Risk 50/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity76% × 45%Impact severity (EG Severity): CVSS 7.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation40% × 40%EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.4%
- EPSS %ILE
- 36th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.6): severity, escalated by confirmed exploitation. This CVE's 7.6 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.6 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track 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). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
September 23, 2026
Last Modified
September 23, 2026
Advisory Details (4)
Auto-updated Sep 23, 2026v7.3.0
Patch available: OpenC3/cosmos v7.3.0
https://github.com/OpenC3/cosmos/releases/tag/v7.3.0commit 10371f8f410b (OpenC3/cosmos)
Fix landed in OpenC3/cosmos commit 10371f8f410b — awaiting tagged release
https://github.com/OpenC3/cosmos/commit/10371f8f410b9ad588f98dfa3befaaacb6587cd3Make button eval safe
Fix merged in OpenC3/cosmos PR #3560 on 2026-07-14 — awaiting tagged release
https://github.com/OpenC3/cosmos/pull/3560Stored, cross-user XSS via Telemetry screen BUTTON widget · Advisory · OpenC3/cosmos · GitHub
https://github.com/OpenC3/cosmos/security/advisories/GHSA-gvf2-2rh5-mpgfVendor 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.
Patch Availability(1)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| npm | @openc3/vue-common @ 7.3.0 (fixes >= 5.0.6, <= 7.2.1) | — | ghsa |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| @openc3/vue-common | — |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 48× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-11-01 07:38 UTCGHSA enrichmentGHSA-gvf2-2rh5-mpgf · GitHub severity HIGH · GitHub CVSS 7.6
- 2026-11-01 07:38 UTCEG score recompute
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-27 19:00 UTCEG score recompute
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-25 14:01 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-20 08:12 UTCEG score recompute
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-18 03:12 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 31st percentile
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- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-13 06:58 UTCEG score recompute
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-12 15:37 UTCEG score recompute
- 2026-10-11 19:23 UTCEG score recompute
- 2026-10-11 16:39 UTCEG score recompute
- 2026-10-11 13:58 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-11 04:19 UTCEG score recompute
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 31st percentile
- 2026-10-10 04:42 UTCEG score recompute
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-08 17:17 UTCEG score recompute
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-08 05:31 UTCEG score recompute
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-06 15:40 UTCEG score recompute
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-06 03:49 UTCEG score recompute
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-05 04:03 UTCEG score recompute
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-03 16:42 UTCEG score recompute
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-03 04:56 UTCEG score recompute
- 2026-10-02 05:23 UTCEG score recompute
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-09-30 17:59 UTCEG score recompute
- 2026-09-29 18:16 UTCEG score recompute
- 2026-09-29 15:24 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-09-29 06:00 UTCEG score recompute
- 2026-09-27 18:39 UTCEG score recompute
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-09-26 19:05 UTCEG score recompute
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-09-26 07:16 UTCEG score recompute
- 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-09-24 19:56 UTCEG score recompute
- 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-09-23 20:22 UTCEG score recompute
- 2026-09-23 19:39 UTCEG score recompute
- 2026-09-23 19:26 UTCEG score recompute
- 2026-09-23 18:59 UTCEG score recomputeFirst assessed: 7.6 HIGH
- 2026-09-23 18:59 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-77394?
When was the CVE record for CVE-2026-77394 published?
Is CVE-2026-77394 actively exploited?
What is the CVSS score of CVE-2026-77394?
How do I remediate CVE-2026-77394?
Dependency Blast Radius
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