CVE-2026-78501CWE-77CWE-923command-injection

CVE-2026-78501

High · published September 18, 2026

CVSS v3.1
8.6
EPSS
1%
Percentile
44.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.6 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00540 · 44.6th percentile
Weaknesses
CWE-77 · Improper Neutralization of Special Elements used in a Command ('Command Injection'); CWE-923 · Improper Restriction of Communication Channel to Intended Endpoints
Published
2026-09-18T03:18Z
Affected products (1)
ProductVersionsFixed in
microsoft/365_copilot_chatall versions—
References (1)
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78501 · [email protected]
EPSS history
Timeline
  • 19 SEP 03:54Z
    EPSS moved — → 0%
    epss
  • 17 SEP 22:55Z
    Microsoft 365 Copilot Business Chat Information Disclosure Vulnerability
    cvelistv5