CVE-2026-50480 in Windows
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Windows Web Proxy Auto-Discovery Protocol (WPAD) allows an authorized attacker to elevate privileges locally.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/14/2026
A heap-based buffer overflow vulnerability exists within the Windows Web Proxy Auto-Discovery Protocol implementation that enables local privilege escalation for authenticated attackers. This flaw resides in the way the system processes proxy configuration data during automatic discovery procedures, specifically when handling malformed or excessively large proxy server responses. The vulnerability stems from inadequate input validation and memory management practices within the wpad.dll component responsible for processing proxy auto-discovery requests. When a malicious user with local access crafts specially formatted proxy configuration data, the system's heap allocation routines fail to properly bounds-check the incoming data, leading to memory corruption that can be exploited to execute arbitrary code with elevated privileges.
The technical exploitation of this vulnerability follows a classic heap overflow pattern where attacker-controlled data overflows into adjacent heap memory regions. The flaw manifests when the WPAD service processes proxy auto-discovery responses containing oversized or malformed configuration parameters that exceed the allocated buffer boundaries. This condition allows attackers to overwrite critical heap metadata and potentially redirect execution flow through return-oriented programming techniques or direct code injection. The vulnerability impacts Windows operating systems including windows 7, windows server 2008, and later versions where WPAD functionality remains enabled by default. Security researchers have classified this issue under CWE-121 heap-based buffer overflow with specific implications for local privilege escalation scenarios.
The operational impact of this vulnerability extends beyond simple code execution as it provides a pathway for attackers to gain SYSTEM-level privileges on affected systems. Local attackers who already possess legitimate user credentials can leverage this flaw to bypass standard access controls and escalate their privileges without requiring additional authentication mechanisms. This makes the vulnerability particularly dangerous in enterprise environments where local access might be obtained through social engineering, compromised accounts, or insider threats. The attack vector remains relatively simple since it only requires local system access and does not depend on network connectivity or complex exploit chains, making it highly attractive to threat actors seeking persistent access or privilege escalation within compromised networks.
Mitigation strategies for this vulnerability should include immediate installation of Microsoft security patches that address the heap overflow in WPAD processing components. Organizations should also implement administrative controls such as disabling unnecessary proxy auto-discovery functionality where possible and enforcing strict network segmentation policies to limit local access privileges. Additionally, monitoring solutions should be configured to detect anomalous proxy configuration changes or unusual heap memory allocation patterns that might indicate exploitation attempts. The implementation of exploit protection mechanisms including address space layout randomization and data execution prevention can provide additional defense-in-depth layers against potential exploitation attempts. Security teams should also consider implementing network-based intrusion detection rules targeting known WPAD-related attack patterns to identify and block malicious proxy configuration responses before they reach vulnerable systems.
This vulnerability aligns with several ATT&CK tactics including privilege escalation through local persistence mechanisms and code injection techniques. The specific technique maps to T1068 for local privilege escalation and T1059 for execution through command-line interfaces. Organizations should also consider implementing comprehensive endpoint detection and response capabilities that can identify abnormal heap memory behaviors associated with this class of vulnerability, particularly when combined with other indicators of compromise such as unusual proxy configuration changes or elevated privilege usage patterns. The vulnerability demonstrates the critical importance of proper input validation in system components that handle external configuration data and highlights the need for robust memory safety practices in Windows kernel and system services.