PT-2026-38574 · Microsoft · M365 Copilot

Es7Evam + 1 · Published 2026-05-07 · Updated 2026-05-08 · CVE-2026-26129

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Name of the Vulnerable Software and Affected Versions M365 Copilot (affected versions not specified)

Description Improper neutralization of special elements in Copilot Business Chat allows an unauthorized attacker to disclose information over a network.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Weakness Enumeration

CWE-138

Related Identifiers

CVE-2026-26129

Affected Products

M365 Copilot

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-26129 · Security Note
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26129 · Vendor Advisory
• https://twitter.com/IntCyberDigest/status/2052864105153724723 · Twitter Post
• https://twitter.com/windowsforum/status/2052502589644603865 · Twitter Post