SB2026031105 - Multiple vulnerabilities in Microsoft Excel

Description

This security bulletin contains information about 5 secuirty vulnerabilities.

1) Untrusted Pointer Dereference (CVE-ID: CVE-2026-26112)

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

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

2) Use-after-free (CVE-ID: CVE-2026-26107)

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 Office file and execute arbitrary code on the target system.

3) Heap-based buffer overflow (CVE-ID: CVE-2026-26108)

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

The vulnerability exists due to a boundary error in Microsoft Excel. A remote attacker can trick a victim to open a specially crafted Office file, trigger a heap-based buffer overflow and execute arbitrary code on the target system.

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

4) Out-of-bounds read (CVE-ID: CVE-2026-26109)

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 trigger an out-of-bounds read error and read contents of memory on the system, leading to arbitrary code execution.

5) Cross-site scripting (CVE-ID: CVE-2026-26144)

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data in Microsoft Excel. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26112
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26107
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26108
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26109
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26144