CVE-2026-83705 in Windows
Summary
by MITRE • 10/14/2026
Exposure of sensitive system information to an unauthorized control sphere in Windows HTTP.sys allows an authorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified involves the Microsoft Hypertext Transfer Protocol (HTTP) service, commonly referred to as http.sys within the Windows operating system architecture. This core component is responsible for handling low-level HTTP protocol processing and serves as a critical interface between user-mode applications and kernel-mode drivers. The specific flaw centers on an improper exposure of sensitive system information to an unauthorized control sphere, which fundamentally represents a failure in access control mechanisms designed to isolate privileged data from less trusted contexts. While the description notes that an authorized attacker can exploit this condition locally, it is important to contextualize this within the broader landscape of privilege escalation and information disclosure risks inherent in complex kernel subsystems. The term "authorized attacker" typically implies an entity with some level of legitimate access to the system, such as a standard user account or a service running under restricted privileges, rather than a completely external unauthenticated actor. This distinction is crucial because it highlights that the vulnerability does not allow for initial remote code execution from the internet but instead facilitates lateral movement or privilege escalation after an attacker has already gained a foothold on the machine through other means.
From a technical perspective, http.sys manages connections and processes HTTP requests before passing them to higher-level application frameworks like IIS or ASP.NET. When this component fails to properly validate access controls for certain internal data structures or diagnostic information, it creates a pathway for local information disclosure. The sensitive system information in question may include kernel memory contents, configuration details of running services, or other artifacts that can aid an attacker in mapping the target environment. By leveraging this flaw, an adversary can gather intelligence about the underlying operating system version, installed patches, and potentially cryptographic keys or session tokens stored in memory. This type of vulnerability aligns closely with CWE-200: Information Exposure, which covers scenarios where sensitive information is made available to unauthorized actors without necessarily leading to immediate code execution. The exposure occurs because the http.sys driver does not adequately restrict access to specific internal states or debug interfaces that should remain isolated from user-mode processes lacking elevated privileges.
The operational impact of this vulnerability extends beyond simple data leakage, as it significantly lowers the barrier for subsequent attacks. An attacker who successfully exploits this information disclosure can use the gathered intelligence to craft more precise exploitation attempts against other components on the system. For instance, knowing specific kernel addresses or service configurations allows an attacker to bypass address space layout randomization (ASLR) defenses or identify vulnerable services that may be running with higher privileges. This aligns with ATT&CK technique T1083: File and Directory Discovery, as well as T1057: Process Discovery, where the goal is to enumerate system resources to plan further actions. In a multi-tenant environment or on servers hosting multiple applications, this vulnerability could lead to cross-user data leakage, compromising confidentiality guarantees expected in shared infrastructure. Furthermore, if the disclosed information includes authentication tokens or session identifiers, it could directly result in account takeover scenarios, thereby impacting integrity and availability as well.
Mitigation strategies for this type of vulnerability primarily involve applying vendor-supplied security updates that patch the underlying code flaws within http.sys. Organizations should prioritize deploying these patches across all affected Windows systems to close the information disclosure channel. In addition to patching, implementing strict network segmentation can limit the potential blast radius if an attacker gains local access. Restricting administrative privileges and enforcing least-privilege principles ensures that fewer accounts have the ability to interact with sensitive system components, thereby reducing the attack surface for this specific flaw. Security monitoring solutions should be configured to detect anomalous behavior associated with information gathering activities, such as unusual reads from kernel memory or unexpected interactions with http.sys endpoints. Regular vulnerability assessments and penetration testing can help identify similar misconfigurations before they are exploited in the wild. Ultimately, maintaining a robust patch management policy is the most effective defense against known vulnerabilities that compromise system integrity through unauthorized data exposure.