CVE record · CVE-2026-50517

Microsoft M365 Copilot Remote Code Execution Vulnerability

CVSS 9.9 CriticalCriticalEPSS 0.017 · 77th percentile

Critical, because:

CVSS score 9.9: 9.0 or more.

Published by the CVE Program (CNA: microsoft) at 24 Jul 2026, 00:01 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
Microsoft	Microsoft 365 Copilot	affected -

Identifiers: CVE-2026-50517
CNA: microsoft
Weakness (CWE): CWE-502
Tags: Microsoft 365 Copilot
Insecure deserialization
Published: 24 Jul 2026
Updated: 1 Nov 2026

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
9.9	Critical	3.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C	CNA (microsoft)

CISA KEV Not listed.
EPSS 0.017, the 77th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

24 Jul 2026, 00:01 UTC Confirmed by the CVE List

Sources

References from the CNA

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50517 vendor-advisorypatch

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.