Description

Buffer over-read in Windows Event Logging Service allows an authorized attacker to disclose information locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-11T17:18:09.070Z",
  "pubdate": "2026-08-11T17:18:09.070Z",
  "executiveSummary": "A buffer over-read vulnerability exists within the Windows Event Logging Service, specifically affecting local event logging mechanisms within the Microsoft Windows operating system. This vulnerability allows an authorized local attacker to perform unauthorized information disclosure, potentially exposing sensitive memory contents or operational data that should otherwise remain protected.\nThe core risk implication involves the breach of confidentiality, as unauthorized read access to out-of-bounds memory regions can leak critical system pointers, cryptographic material, or internal state data. Exploitation of this flaw requires the attacker to possess prior authorization and local access to the target system, meaning unauthenticated remote attackers cannot leverage this vulnerability directly.\nThe attack vector is strictly local, necessitating that the threat actor has already established a foothold on the target host with sufficient execution privileges to interact with the vulnerable service. No specific complex exploitation requirements beyond local authorization are detailed in the standard operational parameters, making standard privilege management and least-privilege enforcement critical components of the risk profile.",
  "technicalDetails": "The root cause of the vulnerability stems from improper bounds checking within the Windows Event Logging Service when processing specific log data structures or parsing input parameters. When the vulnerable component handles specially crafted requests, it fails to adequately validate the size of the input relative to the allocated memory buffer, resulting in a buffer over-read condition.\nThe vulnerable component resides in the core binaries responsible for handling event log records and maintaining log state within the Windows Event Logging Service. Because the service executes with elevated system privileges, improper memory handling during internal read operations can cause the service to read past the intended boundary of a heap- or stack-allocated buffer into adjacent memory regions.\nThe attack flow proceeds as follows: First, the authorized attacker establishes local execution context on the target Windows system. Second, the attacker interacts with the Windows Event Logging Service via local inter-process communication mechanisms, APIs, or command interfaces exposed by the service. Third, the attacker supplies a maliciously crafted payload or sequence of parameters designed to trigger the out-of-bounds read condition during log processing.\nAs the vulnerable function executes, it reads data from memory addresses outside the legitimate bounds of the allocated buffer. This extraneous memory data is subsequently processed or potentially returned to the caller within error messages, logging outputs, or application responses, depending on how the service handles the malformed input. This behavior constitutes the information disclosure mechanism.\nAuthentication and privilege requirements dictate that the attacker must be authorized—typically possessing low-privileged local user access—to interact with the logging service interfaces. Network exposure is non-existent for this specific local vector, as the attack surface is restricted to local system boundaries. Post-exploitation impact is centered primarily on confidentiality loss, where leaked memory contents may be analyzed by the attacker to facilitate subsequent local privilege escalation or to bypass additional security controls such as Address Space Layout Randomization if specific memory addresses are revealed."
}