CVE-2026-21509
HIGHCISA KEVEPSS 99th pctlDescription
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
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
Exploit Intelligence
Very high risk: more likely to be exploited than 99% of all known CVEs.
Microsoft Office Security Feature Bypass Vulnerability
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.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Remediation due: 2026-02-16
References
Related Vulnerabilities
Other CWE-807 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2026-34486 | High | 7.5 | 22% | - | Fix |
| CVE-2024-13974 | High | 8.1 | 6.7% | - | Fix |
| CVE-2021-41129 | High | 8.1 | 1.7% | - | Fix |
| CVE-2026-21514 | High | 7.8 | 1.5% | KEV | - |
| CVE-2025-49827 | Critical | 9.8 | 1.4% | - | Fix |
| CVE-2021-31999 | High | 8.8 | 1.1% | - | Fix |
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-25.