High severity · published May 7, 2026
CVE-2026-26164
M365 Copilot Information Disclosure Vulnerability
7.5
CVSS
0.8%
EPSS
No
On KEV
Description
Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 56% 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-2026-26164
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-26164
Vendor Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26164
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