Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

The Microsoft Excel Products are missing a security update. It is, therefore, affected by the following vulnerabilities:

  - Multiple remote code execution vulnerabilities that attackers can exploit to bypass authentication and     execute unauthorized arbitrary commands. (CVE-2026-20946, CVE-2026-20950, CVE-2026-20955, CVE-2026-20956,     CVE-2026-20957)

  - A security feature bypass vulnerability. (CVE-2026-20949)     Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of Microsoft Office for Mac installed on the remote host is affected by multiple vulnerabilities as referenced in the january-13-2026 advisory.

  - Use after free in Microsoft Office allows an unauthorized attacker to execute code locally.
    (CVE-2026-20952, CVE-2026-20953)

  - Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to     execute code locally. (CVE-2026-20957)

  - Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
    (CVE-2026-20946)

  - Improper access control in Microsoft Office Excel allows an unauthorized attacker to bypass a security     feature locally. (CVE-2026-20949)

  - Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code     locally. (CVE-2026-20955, CVE-2026-20956)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Microsoft Excel Products are missing a security update. They are, therefore, affected by multiple remote code execution vulnerabilities. An attacker can exploit these to bypass authentication and execute unauthorized arbitrary commands. (CVE-2026-20946, CVE-2026-20950, CVE-2026-20957)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Microsoft Office Online Server installation on the remote host is missing security updates. It is, therefore, affected by the following vulnerabilities:

  - Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
    (CVE-2026-20950)

  - Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code     locally. (CVE-2026-20955)

  - Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to     execute code locally. (CVE-2026-20957)

ID	Name	Product	Family	Severity
283873	Security Updates for Microsoft Excel Products C2R (January 2026)	Nessus	Windows	high
283480	Security Updates for Microsoft Office Products (January 2026) (macOS)	Nessus	MacOS X Local Security Checks	high
283477	Security Updates for Microsoft Excel Products (January 2026)	Nessus	Windows : Microsoft Bulletins	high
283462	Security Updates for Microsoft Office Online Server (January 2026)	Nessus	Windows : Microsoft Bulletins	high

Detections

Analytics

CVE-2026-20950

high

Tenable Plugins

high

high

high

high