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Vulnerability record · CVE-2026-26129 · published 7 May 2026

CVE-2026-26129: Microsoft 365 copilot chat vulnerability

Microsoft · 365 Copilot Chat

Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.

7.5 CVSS 3.1 High EPSS 1.0% · top 37.8% CWE-138 · CWE-138
7.5CVSS 3.1 base score
1.0%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References
17 Jun 2026Last modified by NVD

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26129 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.9CVE-2026-26137Microsoft 365 copilot chat server-side request forgery (ssrf) vulnerabilityServer-side request forgery (ssrf) in Microsoft Exchange allows an authorized attacker to elevate privileges over a network.EPSS 0.72%9.3CVE-2025-59286Microsoft 365 copilot chat command injection vulnerabilityImproper neutralization of special elements used in a command ('command injection') in Copilot allows an unauthorized attacker to disclose informatio…EPSS 0.57%9.3CVE-2025-59272Microsoft 365 copilot chat command injection vulnerabilityImproper neutralization of special elements used in a command ('command injection') in Copilot allows an unauthorized attacker to perform information…EPSS 0.57%7.5CVE-2026-26164Microsoft 365 copilot chat injection vulnerabilityImproper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose infor…EPSS 1.0%7.5CVE-2025-53774Microsoft 365 copilot chat command injection vulnerabilityMicrosoft 365 Copilot BizChat Information Disclosure VulnerabilityEPSS 0.61%7.5CVE-2025-53787Microsoft 365 copilot chat command injection vulnerabilityMicrosoft 365 Copilot BizChat Information Disclosure VulnerabilityEPSS 0.71%

Source: NIST National Vulnerability Database (record CVE-2026-26129), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.