CVE-2026-62753 in Windows
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical heap-based buffer overflow within the Windows HTTP.sys kernel driver that enables local privilege escalation for authenticated attackers. The flaw exists in the handling of HTTP protocol requests within the kernel space, specifically when processing malformed or excessively large HTTP headers that trigger improper memory allocation and copying operations. The vulnerability manifests when the HTTP.sys component fails to properly validate input lengths before copying data into heap-allocated buffers, creating a condition where an attacker can overwrite adjacent memory regions with controlled data. This type of vulnerability falls under CWE-121 Heap-based Buffer Overflow, which is classified as a serious weakness that can lead to arbitrary code execution and privilege escalation. The attack vector requires local authentication since the vulnerability exists within kernel-level components that are only accessible to authenticated users with sufficient privileges to establish HTTP connections or interact with the HTTP.sys service. From an operational perspective, this vulnerability presents significant risk as it allows attackers who already have user-level access to escalate their privileges to system level, effectively granting them complete control over the affected Windows system. The exploitation process typically involves crafting malicious HTTP requests that trigger the buffer overflow condition, which can then be leveraged to execute arbitrary code with kernel-level privileges. This vulnerability directly maps to attack techniques described in the ATT&CK framework under privilege escalation tactics and techniques such as exploit for privilege escalation and process injection methods. The impact extends beyond individual system compromise as successful exploitation can enable attackers to establish persistent access, escalate to domain administrator privileges, or use the compromised system as a foothold for lateral movement within network environments. Organizations should prioritize patching this vulnerability immediately through Microsoft's regular security updates, while implementing additional mitigations such as disabling unnecessary HTTP services, restricting local authentication where possible, and monitoring for anomalous HTTP traffic patterns that might indicate exploitation attempts. Network segmentation and least privilege principles should be reinforced to limit the potential damage from successful exploitation, as the vulnerability can be particularly dangerous in enterprise environments where local access might be more readily available than anticipated. The technical nature of this flaw also highlights the importance of proper input validation and memory management practices within kernel-mode drivers, emphasizing that even authenticated users with legitimate access can pose significant threats when vulnerabilities exist in core system components.