Live › vulnerability › CVE-2026-21509
Go to dashboardMicrosoft Office contains a security feature bypass where an untrusted input is relied on in a security decision, letting an unauthorized attacker get around a protection. CISA lists it as actively exploited in the wild.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 19:11 UTC, 5h before NVD. All times on this page are UTC.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| Microsoft Office | vendor | – | – |
| microsoft 365 apps | vendor | – | – |
| microsoft office | vendor | = 2016 | – |
| microsoft office | vendor | = 2019 | – |
| microsoft office long term servicing channel | vendor | = 2021 | – |
| microsoft office long term servicing channel |
| vendor |
| = 2024 |
| – |
Unknown from the sources.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
Microsoft Office contains a security feature bypass vulnerability in which reliance on untrusted inputs in a security decision in Microsoft Office could allow an unauthorized attacker to bypass a security feature locally. Some of the impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.
CISA 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.
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