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Vulnerabilities

Vulnerability · CVE-2026-63533

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

Published Aug 11, 2026 · catalog updated Oct 14, 2026 · 365 apps

Check if you run it

No confirmed exploitation is on record for CVE-2026-63533. EPSS is 0.47%. Act only if a listed version of 365 apps is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.47%
Remediation
Advisory link
Affected products
cpe microsoft/365 apps · cpe microsoft/microsoft 365 · cpe microsoft/office 2016 · cpe microsoft/office 2019 · cpe microsoft/office 2021

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe microsoft/365 appsversion unspecified
  • cpe microsoft/microsoft 365version unspecified
  • cpe microsoft/office 2016version unspecified
  • cpe microsoft/office 2019version unspecified
  • cpe microsoft/office 2021version unspecified

How to fix CVE-2026-63533

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-63533. EPSS is 0.47%. Act only if a listed version of 365 apps is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-122: Heap-based Buffer Overflow. EPSS 0.47%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 11, 2026 · NIST NVD

    Detected

    Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

  2. Oct 14, 2026 · NIST NVD

    Updated

    Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

Sources

  • CVE.orgVulnerability recordCVE-2026-63533

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-63533

    30-day exploitation probability 0.5%

    first.org
  • NIST NVDVulnerability recordCVE-2026-63533

    Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.