High severity · published Sep 17, 2026
CVE-2026-78501
Microsoft 365 Copilot Business Chat Information Disclosure Vulnerability
8.6
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 45% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
M3
Microsoft 365 Copilot's Business Chat · Microsoft
All versions, or not specified · source: vendor
3C
365 Copilot Chat · Microsoft
All versions, or not specified · source: NVD
Affected product
M3
Microsoft 365 Copilot's Business Chat
Microsoft
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-78501
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-78501
vendor-advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78501
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