Description

Stack-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": "2026-08-11T17:19:03.010Z",
  "pubdate": "2026-08-11T17:19:03.010Z",
  "executiveSummary": "A stack-based buffer overflow vulnerability has been identified within Microsoft Office Excel. This security flaw enables an unauthorized, local attacker to execute arbitrary code within the context of the current user. The vulnerability stems from improper bounds checking during the parsing of maliciously crafted spreadsheet files, leading to memory corruption on the stack. If successfully exploited, the vulnerability can result in complete system compromise or application instability depending on the privileges of the targeted user. Risk implications are significant for environments where users frequently handle untrusted Office documents. Attack capabilities include local code execution without requiring prior authentication. Exploitation requirements typically involve social engineering to trick a user into opening a specially crafted Excel file.",
  "technicalDetails": "The vulnerability is a classic stack-based buffer overflow residing in the file-parsing logic of Microsoft Office Excel. The root cause is the failure of the application to properly validate the length of input data copied into a fixed-size stack buffer during the processing of specific record structures within an Excel document. When a user opens a maliciously crafted spreadsheet, the vulnerable component attempts to read excessively long data fields into allocated stack memory without enforcing strict boundary constraints. This architectural oversight allows an attacker to overflow the stack buffer, overwriting adjacent stack memory locations, including saved frame pointers and return addresses. The attack flow commences when the victim opens the malicious file using Microsoft Office Excel. The application parses the malicious record structures, triggering the buffer overflow condition as input data exceeds the boundaries of the destination buffer. By carefully crafting the payload within the document, an attacker can overwrite the instruction pointer with a memory address pointing to shellcode or implement return-oriented programming (ROP) chains to bypass security mitigations such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR). The exploitation method does not require authentication or elevated privileges, as it executes under the security context of the locally logged-in user. Post-exploitation impact includes arbitrary code execution, potential escalation of privileges if running alongside vulnerable system configurations, installation of malware, and unauthorized access to sensitive user data and local network resources."
}