Description

Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:19:03.793Z",
  "pubdate": "2026-08-11T17:19:03.793Z",
  "executiveSummary": "This vulnerability is classified as a heap-based buffer overflow affecting Microsoft Office Excel.\nThe primary impact of successful exploitation is local code execution, allowing an adversary to execute arbitrary commands or payloads within the context of the current user.\nThe affected system component is Microsoft Office Excel, which fails to adequately bound-check dynamic memory allocations during the parsing of malformed spreadsheet files.\nThe risk implications are severe, as arbitrary code execution can lead to complete system compromise, data exfiltration, or lateral movement within the enterprise network if the executing user possesses elevated privileges.\nAttacker capabilities require local access or user interaction to induce the target into opening a maliciously crafted spreadsheet file.\nExploitation requirements include the victim opening a specially crafted file designed to trigger the heap corruption condition within the memory management structures of Microsoft Office Excel.",
  "technicalDetails": "The vulnerability stems from a heap-based buffer overflow within Microsoft Office Excel during the handling and parsing of specific record structures inside spreadsheet files.\nThe root cause involves inadequate validation of size parameters associated with dynamic memory allocation operations on the heap, leading to a discrepancy between the calculated buffer size and the actual data copied into the allocated chunk.\nWhen a user opens a maliciously crafted Microsoft Office Excel document, the application parses the embedded malicious structures, causing heap corruption by writing data past the boundaries of the allocated heap buffer.\nThis out-of-bounds write overwrites adjacent heap metadata or critical function pointers residing in the heap memory space.\nAn unauthorized attacker can leverage this memory corruption condition to hijack the application control flow, redirecting execution to attacker-supplied shellcode or leveraging return-oriented programming (ROP) chains.\nThe vulnerable component is the file parsing engine of Microsoft Office Excel responsible for interpreting proprietary or open file formats.\nAuthentication requirements are none regarding network access, but local execution or user interaction via document opening is required.\nPrivilege requirements are minimal, as the exploit executes under the standard security context of the locally logged-in user running Microsoft Office Excel.\nNetwork exposure is low, as the attack vector is primarily local or reliant on social engineering to deliver the malicious document via email or file share.\nPost-exploitation impact includes arbitrary local code execution, potential installation of persistent malware, and compromise of user-accessible data."
}