Description

Use after free in Winlogon allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.0",
  "pubDate": "2026-08-11T17:18:18.207Z",
  "pubdate": "2026-08-11T17:18:18.207Z",
  "executiveSummary": "A use-after-free vulnerability exists within the Winlogon component, allowing an authorized local attacker to elevate privileges.\nThe vulnerability affects Windows Logon (Winlogon), a core operating system service responsible for handling secure logon and logoff procedures.\nSuccessful exploitation of this flaw results in local privilege escalation, potentially enabling an adversary to execute arbitrary code with administrative or SYSTEM-level privileges.\nThe risk implications are severe, as compromise of the Winlogon process grants full control over the affected host system, bypassing standard security boundaries.\nAttacker capabilities require local access to the target machine.\nThe primary exploitation requirement is that the attacker must already be authorized or authenticated on the local system with the ability to execute code before initiating the exploit sequence against the vulnerable Winlogon component.",
  "technicalDetails": "The vulnerability stems from a use-after-free condition located in the Winlogon component of the operating system.\nA use-after-free vulnerability typically occurs when a program continues to use a pointer after the memory chunk it references has been deallocated or freed.\nIf memory management fails to nullify pointers properly following resource cleanup, a dangling pointer is left accessible.\nAn authorized local attacker can manipulate heap memory allocations and timing to trigger the reuse of the freed memory block.\nBy carefully crafting input or triggering specific state transitions within Winlogon, the attacker forces the application to reference the dangling pointer.\nThe attack flow proceeds as follows: first, the attacker establishes a local execution context on the target host; second, the attacker interacts with the Winlogon service using specific API calls or inter-process communication mechanisms designed to induce a resource allocation and deallocation cycle; third, the attacker executes a heap spraying or memory grooming technique to place controlled data into the memory address space previously occupied by the freed Winlogon object; finally, when Winlogon accesses the dangling pointer, it processes the attacker-controlled data as a valid object structure.\nThis improper handling leads to memory corruption and allows the redirection of execution flow.\nBecause Winlogon runs with high privileges necessary for managing user sessions and authentication interfaces, hijacking its control flow grants the adversary immediate privilege escalation.\nThe affected component is the Winlogon service, which operates locally with elevated system privileges.\nNetwork exposure is absent, as the attack vector is strictly local and cannot be leveraged remotely.\nAuthentication and privilege requirements dictate that the attacker must possess local execution capability and be an authorized user on the system to interact with the vulnerable component."
}