Description

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-11T17:19:03.270Z",
  "pubdate": "2026-08-11T17:19:03.270Z",
  "executiveSummary": "This vulnerability is classified as an out-of-bounds read flaw affecting Microsoft Office Excel. The security defect enables an unauthorized local attacker to disclose sensitive information, potentially leading to unauthorized data exposure from memory spaces associated with the application.\nThe primary impact of this vulnerability is confidentiality loss. By exploiting the flaw, an adversary can read adjacent memory contents, which may contain sensitive data structures, user information, or cryptographic keys processed within the context of the vulnerable application.\nThe affected product is Microsoft Office Excel. The risk implications include the potential leakage of critical system or user data, which could be leveraged to facilitate subsequent, more sophisticated attacks or to compromise other system components through intelligence gathering.\nAttacker capabilities required for successful exploitation involve the ability to execute code locally or entice a target user to open a specially crafted malicious file using the vulnerable Microsoft Office Excel software. Exploitation requirements rely on the processing of malformed input data that triggers the out-of-bounds read condition during parsing operations.",
  "technicalDetails": "The root cause of the vulnerability stems from improper bounds checking within Microsoft Office Excel when parsing specific file structures or memory buffers. Specifically, the vulnerable component fails to adequately validate the size and boundaries of input data against allocated buffer lengths before performing read operations.\nThe vulnerable component resides within the file parsing and data processing modules of Microsoft Office Excel. These modules are responsible for interpreting complex document formats and extracting data elements into internal memory representations during document loading and rendering.\nExploitation occurs when an unauthorized attacker constructs a malformed input file or manipulates data parameters that trick the application into reading past the end of an allocated buffer. The attack flow begins when the user opens the maliciously crafted file within Microsoft Office Excel. As the application parses the corrupted data structures, the internal read pointer exceeds the legitimate boundary limits defined for the buffer.\nThe payload behavior involves capturing the contents of adjacent memory locations that are inadvertently exposed during the out-of-bounds read operation. Because the application lacks sufficient bounds verification, these unauthorized memory contents may be returned or processed in a manner that allows the attacker to glean sensitive information.\nRegarding authentication and privilege requirements, the vulnerability can be exploited locally without requiring elevated privileges. The network exposure is strictly local, necessitating local access to the filesystem or user interaction via the opening of untrusted files. Post-exploitation impact is primarily characterized by information disclosure, where the leaked memory contents provide actionable intelligence for further adversarial objectives."
}