Description

Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:19:05.170Z",
  "pubdate": "2026-08-11T17:19:05.170Z",
  "executiveSummary": "An untrusted pointer dereference vulnerability exists within Microsoft Office Excel, potentially allowing an unauthorized local attacker to achieve arbitrary code execution on the targeted system.\nThe vulnerability resides in the memory management handling of Microsoft Office Excel when parsing specially crafted files. By inducing a user to open a malicious document, an unauthorized adversary can manipulate memory references, resulting in the dereferencing of untrusted pointers.\nSuccessful exploitation of this flaw compromises the integrity and confidentiality of the host operating system, granting the attacker the ability to execute malicious payloads within the context of the current user session.\nWhile the attack requires local access or user interaction—typically via the opening of a malicious file delivered through phishing or external sources—the resulting code execution poses a severe risk to organizational endpoints utilizing affected versions of Microsoft Office Excel.\nSecurity teams must prioritize defensive hardening and monitoring to mitigate the risks associated with local memory corruption and untrusted pointer manipulation vectors.",
  "technicalDetails": "The root cause of the vulnerability stems from improper validation and handling of memory pointers within Microsoft Office Excel. Specifically, the application processes internal data structures derived from untrusted file input without adequately verifying that memory addresses point to valid, expected allocations.\nWhen a specially crafted Excel file is parsed, the vulnerable component attempts to dereference a pointer whose value has been influenced or controlled by the attacker. Because the pointer references an arbitrary or unvalidated memory address rather than a legitimate object or buffer, a memory access violation or controlled memory corruption occurs.\nThe attack flow proceeds as follows: First, the unauthorized attacker crafts a malicious spreadsheet containing manipulated structural records designed to corrupt the application's heap or stack state during parsing. Second, the victim opens the file using an affected version of Microsoft Office Excel. Third, as the parsing engine processes the malformed structures, it resolves and attempts to dereference the untrusted pointer. Finally, the improper pointer dereference triggers a state where control flow can be hijacked, allowing the execution of shellcode or native payloads provided within the input file.\nThe vulnerable component is the file parsing and memory management subsystem of Microsoft Office Excel. Exploitation requires local access, as the victim must interact with the malicious file to initiate the parsing sequence. No authentication or elevated privileges are required to trigger the initial vulnerability, though successful code execution is constrained by the access rights and privilege level of the user running the application.\nPost-exploitation impact includes local code execution, persistence installation, and lateral movement capabilities depending on the privileges of the compromised user session and the presence of endpoint detection mechanisms."
}