High severity7.8NVD Advisory· Published Feb 10, 2026· Updated Jun 17, 2026

CVE-2026-21259

Description

Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally.

Microsoft/365 Apps2 versions
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*+ 1 more
- cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
- cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
Microsoft/Excel3 versions
cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x64:*+ 2 more
- cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x64:*
- cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x86:*
- (no CPE)
Microsoft/Office4 versions
cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*+ 3 more
- cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*
- cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x86:*
- (no CPE)range: 16.0.1
- (no CPE)range: 16.0.0
Microsoft/Office Long Term Servicing Channel4 versions
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:*+ 3 more
- cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:*
- cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x86:*
- cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x64:*
- cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x86:*
Microsoft/Office Online Server2 versions
cpe:2.3:a:microsoft:office_online_server:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:microsoft:office_online_server:*:*:*:*:*:*:*:*range: <16.0.10417.20097
- (no CPE)range: 16.0.0.0
Microsoft/Office Excelllm-fuzzy
Microsoft/Microsoft 365 Apps for Enterprisev5
Range: 16.0.1
Microsoft/Excel 2007 SP3cpe-rescue
Range: 16.0.0.0
Microsoft/Office Visiocpe-rescue
Range: 19.0.0