Critical CVSS 9.9
CVE-2026-50517
NVD analysis in progress
Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.
What this means
- Exposure
- Exploitable remotely over the network, with an ordinary user account and with no action from the victim.
- Impact
- An attacker can read sensitive data, modify or destroy data and take the service offline. The impact spreads beyond the vulnerable component into other parts of the system.
- Weakness
- The application rebuilds an object from attacker-controlled data, which often leads to code execution.
- Likelihood
- Its EPSS score puts short-term exploitation in a middle band: neither negligible nor imminent.
What to doPatch without waiting for the next scheduled cycle.
Read automatically from the CVSS vector, the weakness type (CWE) and the EPSS score. The technical description above remains the one published by NIST.