CVE-2026-21509 (GCVE-0-2026-21509)
Vulnerability from cvelistv5 – Published: 2026-01-26 17:06 – Updated: 2026-01-27 13:34
VLAI?
CISA
Title
Microsoft Office Security Feature Bypass Vulnerability
Summary
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
Severity ?
CWE
- CWE-807 - Reliance on Untrusted Inputs in a Security Decision
Assigner
References
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Impacted products
| Vendor | Product | Version | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Microsoft | Microsoft Office 2019 |
Affected:
19.0.0 , < 16.0.10417.20095
(custom)
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CISA Known Exploited Vulnerability
Data from the CISA Known Exploited Vulnerabilities Catalog
Date added: 2026-01-26
Due date: 2026-02-16
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Used in ransomware: Unknown
Notes: Please adhere to Microsoft’s recommended guidelines to address this vulnerability. Implement all final mitigations provided by the vendor for Office 2021, and apply the interim corresponding mitigations for Office 2016 and Office 2019 until the final patch becomes available. For more information please see: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21509
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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