CVE-2026-88156: microsoft 365_apps Stack-based Buffer Overflow

Vulnerability summary

CVE-2026-88156 is a critical (CVSS 9.8) Stack-based Buffer Overflow vulnerability in microsoft 365_apps. EPSS estimates a 0.98% chance of exploitation in the next 30 days, higher than 61.5% of scored vulnerabilities.

Timeline

1. 13-10-2026
   PublishedVulnerability first disclosed.
2. 20-10-2026
   Last modifiedVulnerability information updated.

Description

Stack-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.

• CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).