CVE-2026-50517

CRITICALPre-NVD 9.99.9—
EchelonGraph scoreHIGH confidence

Score 9.9 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-24. the CNA's CVSS baseline 9.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
Trending — 5 sources updated this week
9.9EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.9Exploit: None knownExposed: 0

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

Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.

CVSS v3
9.9
EG Score
9.9(high)
EG Risk
45(Track)
EG Risk 45/100SSVC: 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
Severity99% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
66%
KEV
Not listed

Published

July 24, 2026

Last Modified

July 26, 2026

Advisory Details (1)

Auto-updated Jul 26, 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-2026-50517

Vendor Advisories for CVE-2026-50517(2)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 25× in last 7d / 25× 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. 2026-07-27 10:17 UTCVendor advisory
  2. 2026-07-27 10:17 UTCGHSA enrichment
  3. 2026-07-27 06:08 UTCVendor advisory
  4. 2026-07-27 06:08 UTCGHSA enrichment
  5. 2026-07-27 02:01 UTCVendor advisory
  6. 2026-07-27 02:01 UTCGHSA enrichment
  7. 2026-07-26 21:54 UTCVendor advisory
  8. 2026-07-26 21:54 UTCGHSA enrichment
  9. 2026-07-26 17:47 UTCEG score recompute
  10. 2026-07-26 17:47 UTCVendor advisory
  11. 2026-07-26 17:47 UTCGHSA enrichment
  12. 2026-07-26 14:54 UTCEPSS rescore
  13. 2026-07-26 13:51 UTCEG score recompute
  14. 2026-07-26 13:51 UTCVendor advisory
  15. 2026-07-26 13:51 UTCGHSA enrichment
  16. 2026-07-26 09:44 UTCVendor advisory
  17. 2026-07-26 09:43 UTCGHSA enrichment
  18. 2026-07-26 03:06 UTCEG score recompute
  19. 2026-07-26 03:06 UTCVendor advisory
  20. 2026-07-26 03:05 UTCGHSA enrichment
  21. 2026-07-25 14:18 UTCEPSS rescore
  22. 2026-07-24 14:18 UTCEPSS rescore
  23. 2026-07-24 00:18 UTCEG score recompute
  24. 2026-07-24 00:18 UTCVendor advisory
  25. 2026-07-24 00:17 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-50517?
CVE-2026-50517 is a critical vulnerability published on July 24, 2026. Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.
When was CVE-2026-50517 disclosed?
CVE-2026-50517 was first published in the National Vulnerability Database on July 24, 2026, with the most recent update on July 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-50517 actively exploited?
CVE-2026-50517 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 33.6% of all scored CVEs.
What is the CVSS score of CVE-2026-50517?
CVE-2026-50517 has a CVSS v4.0 base score of 9.9 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-50517?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-50517, 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-2026-50517

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