CVE-2026-55946: Microsoft Microsoft Copilot

Microsoft Copilot Information Disclosure Vulnerability

CVSS 6.1 MediumEPSS 0.0039 · 33rd percentile

Published by the CVE Program (CNA: microsoft) at 17 Sept 2026, 22:55 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 Copilot	affected -

Identifiers

CVE-2026-55946

CNA

microsoft

Weakness (CWE)

CWE-77

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Microsoft Copilot is affected by an AI command injection vulnerability that allows information disclosure. The source does not list affected versions. An unauthorized attacker can exploit it over a network to disclose information. The source does not list a fix or workaround.

Written 10 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
6.1	Medium	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C	CNA (microsoft)

CISA KEV Not listed.
EPSS 0.0039, the 33rd percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

17 Sept 2026, 22:55 UTC Confirmed by the CVE List
31 Oct 2026, 16:20 UTC First seen by agentprime

Sources

References from the CNA

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55946 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.