# CVE-2026-55946 — Microsoft Copilot

> As of 2026-10-08, CVE-2026-55946 is a MEDIUM-severity vulnerability in Microsoft Copilot, CVSS v3.1 6.1, EPSS 0.3% (30.9th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-55946, most recently “Microsoft September 2026 Cloud Disclosure: 18 Elevation-of-Privilege, Information-Disclosure, and Spoofing Flaws Across Azure and Copilot AI Products, Plus a Windows Secure Kernel EoP (CVE-2026-85921)”.

**Last updated:** 2026-10-08

## What is CVE-2026-55946?

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

The record classifies CVE-2026-55946 under weakness class [CWE-77](https://intel.threadlinqs.com/cwe/CWE-77). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 37 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 6.1 — MEDIUM (`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`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 30.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-17, last modified 2026-10-08

## Is CVE-2026-55946 being exploited?

It currently carries a trending score of 37 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Microsoft](https://intel.threadlinqs.com/vendors/microsoft): Copilot

## How to fix CVE-2026-55946

No vendor patch reference has been recorded for CVE-2026-55946 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-55946

1 tracked threat in the Threadlinqs corpus references CVE-2026-55946, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Microsoft September 2026 Cloud Disclosure: 18 Elevation-of-Privilege, Information-Disclosure, and Spoofing Flaws Across Azure and Copilot AI Products, Plus a Windows Secure Kernel EoP (CVE-2026-85921)](https://intel.threadlinqs.com/threat/TL-2026-2563) — CRITICAL · 2026-09-18

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-10.

**Vendor advisory and patch**

- [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55946)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-55946
Full detection coverage and IOCs for threats exploiting CVE-2026-55946 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp