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": "2026-08-11T17:18:51.180Z",
  "pubdate": "2026-08-11T17:18:51.180Z",
  "executiveSummary": "An integer overflow or wraparound vulnerability has been identified within Microsoft Office. This security flaw enables an unauthorized, locally positioned attacker to achieve arbitrary code execution on the target system.\nThe primary impact of this vulnerability is the potential compromise of system integrity and confidentiality, as successful exploitation permits the execution of malicious payloads within the context of the currently logged-on user.\nThe affected product is Microsoft Office. Risk implications are significant due to the widespread deployment of the software suite and the ability for threat actors to leverage local execution vectors to escalate access or establish persistence.\nAttacker capabilities are constrained to local access requirements, implying that the adversary must already possess a foothold on the target machine or be able to deliver a locally executed malicious file to the victim.\nExploitation requirements include user interaction, typically involving the victim opening a specially crafted document designed to trigger the arithmetic overflow condition within the vulnerable parsing engine of Microsoft Office.",
  "technicalDetails": "The root cause of the vulnerability stems from an integer overflow or wraparound condition during the processing of specific file formats or data structures within Microsoft Office. When the application calculates buffer sizes or memory allocations based on untrusted input derived from document headers or metadata, a failure to properly validate arithmetic boundaries leads to an integer wrap.\nThe vulnerable component involves the memory management and parsing routines responsible for handling structural offsets or allocation lengths within Microsoft Office. Due to the lack of safe arithmetic checking functions, an excessively large or maliciously manipulated value causes the integer variable to wrap around to a small positive number or negative value.\nThis arithmetic anomaly results in a heap-based or stack-based buffer allocation that is significantly smaller than required to hold the subsequent data payload. When the parsing engine proceeds to read or copy data into this undersized buffer, a classic out-of-bounds write occurs, corrupting adjacent heap or stack memory structures.\nThe attack flow proceeds as follows: First, an unauthorized attacker crafts a malicious file containing manipulated structural dimensions or size descriptors designed to induce an integer overflow upon parsing. Second, the file is delivered to the target system via local methods, removable media, or social engineering. Third, the victim opens the file using Microsoft Office. Fourth, the vulnerable parsing routine processes the malformed headers, resulting in an integer wraparound during memory allocation calculations. Fifth, the subsequent memory corruption overwrites critical execution pointers or control data structures.\nAuthentication requirements are nonexistent for the local execution context, as the vulnerability is triggered via local file processing. Privilege requirements dictate that the attacker must operate with standard local user access to execute the binary or manipulate the file on the host. Network exposure is not directly required for the primary exploitation vector, as the flaw manifests locally during document parsing.\nPost-exploitation impact includes local code execution, allowing the threat actor to deploy secondary payloads, install persistence mechanisms, access sensitive user documents, or perform internal reconnaissance from the compromised endpoint."
}