CVE-2026-64911 in Office
Summary
by MITRE • 08/11/2026
Integer overflow or wraparound in Microsoft Office allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical integer overflow condition that occurs within Microsoft Office applications, specifically affecting the handling of numeric values during memory allocation or buffer operations. The flaw arises when an application processes user-supplied data that contains maliciously crafted integer values exceeding the maximum representable value for the given data type, causing the integer to wrap around to a much smaller value. This wraparound behavior creates a scenario where the application calculates an incorrect buffer size or loop iteration count, leading to memory corruption that can be exploited by attackers.
The technical exploitation of this vulnerability typically involves crafting malicious Office documents or files that contain specially formatted data structures designed to trigger the integer overflow during parsing operations. When Microsoft Office processes these malformed inputs, the overflow causes memory allocation calculations to produce unexpectedly small buffer sizes or iteration counts, resulting in memory corruption that can be leveraged for code execution. This type of vulnerability falls under the common weakness enumeration CWE-190, which specifically addresses integer overflow conditions, and represents a variant of the more general CWE-128, dealing with signed integer overflow.
The operational impact of this vulnerability extends beyond simple privilege escalation as it enables local code execution attacks that can bypass modern security controls such as address space layout randomization and data execution protection. Attackers can exploit this condition to execute arbitrary code within the context of the Office application process, potentially leading to full system compromise. The attack surface is particularly concerning given Microsoft Office's widespread deployment across enterprise environments and the common practice of opening email attachments or documents from untrusted sources. This vulnerability aligns with several ATT&CK tactics including initial access through malicious document delivery and privilege escalation through code execution within legitimate application processes.
Mitigation strategies should focus on immediate patch management to address the specific integer overflow conditions in affected Office versions, combined with defensive measures such as enabling exploit protection features and implementing strict file validation policies. Organizations should also consider deploying application whitelisting solutions that restrict execution of untrusted Office documents and implement network segmentation to limit lateral movement if exploitation occurs. Additionally, regular security awareness training for users can help prevent social engineering attacks that deliver malicious documents containing these exploits, while monitoring systems should be configured to detect anomalous Office process behavior that may indicate exploitation attempts.