cve 2026 55139

The cve 2026 55139 tag covers Microsoft’s security fix for an information-disclosure vulnerability in supported Office editions on Windows and macOS. The issue is a memory-access flaw that could allow a local attacker to read data outside the memory area Office intended to access, potentially exposing sensitive information held by the application process. Microsoft rated the vulnerability Important and assigned it a CVSS 3.1 base score of 5.5 in the July 14, 2026 security release. The advisory said it was not publicly disclosed or exploited at publication and assessed future exploitation as unlikely.