SB20260113102 - Multiple vulnerabilities in Microsoft Excel

Main Vulnerability Database SB20260113102

SB20260113102 - Multiple vulnerabilities in Microsoft Excel

Published: January 13, 2026

Security Bulletin ID SB20260113102

CSH Severity

High

Patch available

YES

Number of vulnerabilities 6

Exploitation vector Remote access

Highest impact Code execution

Breakdown by Severity

Low
Medium
High
Critical

Description

This security bulletin contains information about 6 vulnerabilities.

1) Untrusted Pointer Dereference (CVE-ID: CVE-2026-20955)

CWE-ID: CWE-822 - Untrusted Pointer Dereference

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to untrusted pointer dereference in Microsoft Excel. A remote attacker can trick a victim to open a specially crafted file and execute arbitrary code on the system.

2) Improper access control (CVE-ID: CVE-2026-20949)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions in Microsoft Excel. A remote attacker can trick a victim to open the malicious workbook, enable editing and then click the attacker‑supplied Quick Access Toolbar (QAT) button to bypass a security feature.

3) Use-after-free (CVE-ID: CVE-2026-20950)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error in Microsoft Excel. A remote attacker can trick a victim to open a specially crafted file and execute arbitrary code on the target system.

4) Integer underflow (CVE-ID: CVE-2026-20957)

CWE-ID: CWE-191 - Integer underflow

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to integer underflow in Microsoft Excel. A remote attacker can trick a victim to open a specially crafted file, trigger integer underflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

5) Out-of-bounds read (CVE-ID: CVE-2026-20946)

CWE-ID: CWE-125 - Out-of-bounds read

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition in Microsoft Excel. A remote attacker can create a specially crafted file, trick the victim into opening it, trigger an out-of-bounds read error and read contents of memory on the system, leading to arbitrary code execution.

6) Untrusted Pointer Dereference (CVE-ID: CVE-2026-20956)

CWE-ID: CWE-822 - Untrusted Pointer Dereference

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to untrusted pointer dereference in Microsoft Excel. A remote attacker can trick a victim to open a specially crafted file and execute arbitrary code on the system.

Remediation

Install update from vendor's website.

References