CVE-2026-21509

Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.

CVSS v3 7.8 HIGH

7.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 1.8 / Impact : 5.9

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509	Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509	US Government Resource

Configurations

Configuration 1 (hide)

OR	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:*

History

No history.

Information

Published : 2026-01-26 18:16

Updated : 2026-01-27 16:19

NVD link : CVE-2026-21509

Mitre link : CVE-2026-21509

CVE.ORG link : CVE-2026-21509

JSON object : View

Products Affected

microsoft

office_long_term_servicing_channel
365_apps
office

CWE

CWE-807

Reliance on Untrusted Inputs in a Security Decision

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