Vulnerability · Published Jul 24, 2026 · Assigned by microsoft
CVE-2026-50517Microsoft M365 Copilot Remote Code Execution Vulnerability
Critical 9.9
In plain English
A critical-severity unsafe deserialization in Microsoft 365 Copilot from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.7% (higher than 77% of all known vulnerabilities).
Severity (CVSS 3.1)9.9Critical
Exploit odds (30 days)1.7%top 22.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft 365 Copilot | - |
Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
References
- Microsoft M365 Copilot Remote Code Execution Vulnerability vendor-advisory, patch