Description

Integer overflow or wraparound in Microsoft Office allows an unauthorized attacker to execute code locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:18:52.280Z",
  "pubdate": "2026-08-11T17:18:52.280Z",
  "executiveSummary": "An integer overflow or wraparound vulnerability has been identified within Microsoft Office, posing significant security risks to affected systems. This software flaw allows an unauthorized local attacker to execute arbitrary code within the context of the current user. The vulnerability resides in how Microsoft Office handles numerical computations, specifically when integer bounds are improperly validated, leading to a wraparound condition that can corrupt memory structures. The primary impact of successful exploitation is local code execution, which may allow an adversary to elevate privileges, install malicious persistence mechanisms, or compromise sensitive data stored within the user environment. Exploitation typically requires the target to open a specially crafted malicious file locally or interact with vulnerable parsing routines. Given the ubiquity of Microsoft Office in enterprise and consumer environments, unmitigated instances of this vulnerability present a notable attack surface for local threat actors or malware payloads already present on the endpoint. Remediation requires applying official vendor patches and adhering to strict least-privilege principles to limit the blast radius of potential code execution.",
  "technicalDetails": "The vulnerability is fundamentally rooted in an integer overflow or wraparound condition occurring during the processing of data structures within Microsoft Office. When the application parses untrusted input—such as file headers, size descriptors, or length fields embedded within documents—it fails to adequately validate arithmetic operations prior to memory allocation or buffer offset calculations. Specifically, when an attacker provides maliciously crafted numerical values designed to exceed the maximum representable value for a specific integer type, the value wraps around to a small integer or zero. This discrepancy between the anticipated size and the actual allocated buffer size results in a heap-based or stack-based buffer overflow condition. To exploit this flaw, an attacker must successfully deliver a specially crafted file to the target system and induce the user or application to open it, thereby invoking the vulnerable parsing function. Once the parsing engine processes the malicious input and incurs the integer wraparound, subsequent memory write or copy operations write data past the boundaries of the undersized buffer. This memory corruption allows the adversary to overwrite adjacent critical data structures, function pointers, or return addresses on the stack. By carefully constructing the payload, the attacker can redirect execution flow to shellcode contained within the input data. Exploitation requires local access and user interaction to open the file, but does not necessitate prior authentication or elevated privileges. The post-exploitation impact includes arbitrary code execution with the permissions of the local user running Microsoft Office, potentially enabling lateral movement, data exfiltration, or complete system compromise depending on the user's privilege level and system hardening configuration."
}