Out-of-bounds read in Microsoft Office - CVE-2026-88153

Vulnerability details

The vulnerability allows a remote attacker to disclose small portions of heap memory.

The vulnerability exists due to an out-of-bounds read in Microsoft Office Excel when processing data. A remote attacker can trigger the out-of-bounds read over a network to disclose small portions of heap memory.

Exploitation requires user interaction. The Preview Pane is not an attack vector.

Affected software

How to mitigate CVE-2026-88153

External References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-88153
• https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates

Related Security Bulletins

• Multiple vulnerabilities in Microsoft Office