CVE-2026-55012: microsoft malware_protection_engine Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-55012 is a high (CVSS 7.8) Heap-based Buffer Overflow vulnerability in microsoft malware_protection_engine. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39% of scored vulnerabilities.

Timeline

1. 14-07-2026
   PublishedVulnerability first disclosed.
2. 08-10-2026
   Last modifiedVulnerability information updated.

Description

Integer overflow or wraparound in Microsoft Defender allows an unauthorized attacker to execute code locally.

• 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().
• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.