CVE-2026-78501

HIGHPre-NVD 7.47.4—
EchelonGraph scoreHIGH confidence

Score 7.4 from GitHub Security Advisory (severity: HIGH) published 2026-09-18. the CNA's CVSS baseline 7.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
Trending — 5 sources updated this week
7.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.4Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Improper neutralization of special elements used in a command ('command injection') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to disclose information over a network.

CVSS v3
7.4
EG Score
7.4(high)
EG Risk
33(Track)
EG Risk 33/100SSVC: Track

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
Severity74% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
41%
KEV
Not listed

Published

September 17, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Sep 17, 2026
Patch available. Sources: microsoft.
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78501

Vendor Advisories for CVE-2026-78501(1)

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

Weakness Classification(2)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 23× in last 7d / 23× 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. 2026-09-19 09:29 UTCVendor advisory
  2. 2026-09-19 09:28 UTCGHSA enrichment
  3. 2026-09-18 20:50 UTCEG score recompute
  4. 2026-09-18 20:50 UTCVendor advisory
  5. 2026-09-18 20:50 UTCGHSA enrichment
  6. 2026-09-18 19:28 UTCEPSS rescore
  7. 2026-09-18 15:23 UTCEG score recompute
  8. 2026-09-18 15:23 UTCVendor advisory
  9. 2026-09-18 15:23 UTCGHSA enrichment
  10. 2026-09-18 14:35 UTCEG score recompute
  11. 2026-09-18 14:35 UTCVendor advisory
  12. 2026-09-18 14:35 UTCGHSA enrichment
  13. 2026-09-18 14:00 UTCEG score recompute
  14. 2026-09-18 14:00 UTCVendor advisory
  15. 2026-09-18 14:00 UTCGHSA enrichment
  16. 2026-09-18 11:57 UTCEG score recompute
  17. 2026-09-18 11:57 UTCVendor advisory
  18. 2026-09-18 11:57 UTCGHSA enrichment
  19. 2026-09-17 23:25 UTCEG score recompute
  20. 2026-09-17 23:25 UTCVendor advisory
  21. 2026-09-17 23:05 UTCEG score recompute
  22. 2026-09-17 23:05 UTCVendor advisory
  23. 2026-09-17 23:04 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-78501?
CVE-2026-78501 is a high vulnerability published on September 17, 2026. Improper neutralization of special elements used in a command ('command injection') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to disclose information over a network.
When was CVE-2026-78501 disclosed?
CVE-2026-78501 was first published in the National Vulnerability Database on September 17, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-78501 actively exploited?
CVE-2026-78501 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 59.0% of all scored CVEs.
What is the CVSS score of CVE-2026-78501?
CVE-2026-78501 has a CVSS v4.0 base score of 7.4 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-78501?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-78501, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-78501

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