CVE-2026-21509

Microsoft Office Security Feature Bypass Vulnerability

Published Jan 26, 2026 CVSS 3.1 · 7.8 High EPSS 70.8% KEV · Listed
Description
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Microsoft office
Microsoft office Long Term Servicing Channel
CPEs cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x86:*
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:*
Vendors & Products Microsoft office
Microsoft office Long Term Servicing Channel
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'active', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics kev

{'dateAdded': '2026-01-26T00:00:00+00:00', 'dueDate': '2026-02-16T00:00:00+00:00'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C'}

Type Values Removed Values Added
Description Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
Title Microsoft Office Security Feature Bypass Vulnerability
First Time appeared Microsoft
Microsoft 365 Apps
Microsoft office 2016
Microsoft office 2019
Microsoft office 2021
Microsoft office 2024
Weaknesses CWE-807
CPEs cpe:2.3:a:microsoft:365_apps:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:office_2016:*:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:office_2019:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:office_2021:*:*:*:*:long_term_servicing_channel:*:*:*
cpe:2.3:a:microsoft:office_2024:*:*:*:*:long_term_servicing_channel:*:*:*
Vendors & Products Microsoft
Microsoft 365 Apps
Microsoft office 2016
Microsoft office 2019
Microsoft office 2021
Microsoft office 2024
References
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
microsoft
Published
Updated
Jul 30, 2026, 8:47 PM
Reserved
Dec 30, 2025, 6:10 PM
Status
Analyzed
Published
Jan 26, 2026, 6:16 PM
Modified
Jun 25, 2026, 5:16 AM