CVE-2025-53766: microsoft 365_copilot Heap-based Buffer Overflow

Vulnerability summary

CVE-2025-53766 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in microsoft 365_copilot. EPSS estimates a 8.19% chance of exploitation in the next 30 days, higher than 94.8% of scored vulnerabilities.

Timeline

1. 12-08-2025
   PublishedVulnerability first disclosed.
2. 13-02-2026
   Last modifiedVulnerability information updated.

Description

Heap-based buffer overflow in Windows GDI+ allows an unauthorized attacker to execute code over a network.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().