Microsoft 365 Copilot Chat vulnerabilities

8 CVEs affecting Microsoft 365 Copilot Chat, 0 known to be exploited (CISA KEV), with EPSS scores. Latest: CVE-2026-78501, published 2026-09-17.

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Known exploited (CISA KEV) first, then by EPSS exploit probability.

• CVE-2026-26164, published 2026-05-07. High severity, CVSS 7.5. EPSS: 1% chance of exploitation in the next 30 days. Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.
• CVE-2026-26129, published 2026-05-07. High severity, CVSS 7.5. EPSS: 1% chance of exploitation in the next 30 days. Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.
• CVE-2026-26137, published 2026-03-19. Critical severity, CVSS 9.9. EPSS: 0.7% chance of exploitation in the next 30 days. Server-side request forgery (ssrf) in Microsoft Exchange allows an authorized attacker to elevate privileges over a network.
• CVE-2025-53787, published 2025-08-07. High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days. Microsoft 365 Copilot BizChat Information Disclosure Vulnerability
• CVE-2025-53774, published 2025-08-07. High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days. Microsoft 365 Copilot BizChat Information Disclosure Vulnerability
• CVE-2025-59286, published 2025-10-09. Critical severity, CVSS 9.3. EPSS: 0.6% chance of exploitation in the next 30 days. Improper neutralization of special elements used in a command ('command injection') in Copilot allows an unauthorized attacker to disclose information over a network.
• CVE-2025-59272, published 2025-10-09. Critical severity, CVSS 9.3. EPSS: 0.6% chance of exploitation in the next 30 days. Improper neutralization of special elements used in a command ('command injection') in Copilot allows an unauthorized attacker to perform information disclosure locally.
• CVE-2026-78501, published 2026-09-17. High severity, CVSS 8.6. EPSS: 0.5% chance of exploitation in the next 30 days. 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.