CVE-2026-88147 in Windows
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in Windows Secure Socket Tunneling Protocol (SSTP) allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a heap-based buffer overflow within the Microsoft Windows Secure Socket Tunneling Protocol, commonly referred to as SSTP. This component is integral to Windows networking infrastructure, facilitating secure remote access by encapsulating Point-to-Point Protocol (PPP) traffic within HTTPS connections. The specific flaw resides in how the SSTP service processes incoming data packets or configuration parameters during the establishment of a tunnel session. When the protocol handler fails to adequately validate the length of input data against the allocated buffer size on the heap, it permits an attacker to write beyond the boundaries of the intended memory region. This type of error is classically categorized under CWE-122, which denotes a heap-based buffer overflow where insufficient bounds checking allows for arbitrary memory writes.
The operational impact of this vulnerability is severe due to its potential for local privilege escalation. Because SSTP often runs with high system privileges as part of the Windows networking stack, successfully exploiting this heap corruption can allow an attacker to overwrite critical control data structures such as function pointers or exception handlers located in adjacent memory regions. By carefully crafting malicious input that triggers the overflow and controls the overwritten values, a local user can redirect code execution to shellcode injected into the process space. This mechanism effectively bypasses standard security boundaries, enabling the attacker to execute arbitrary code with elevated privileges, typically equivalent to SYSTEM level access on the affected host.
From an offensive security perspective, this vulnerability aligns closely with MITRE ATT&CK technique T1068, which covers Exploitation for Privilege Escalation. The attack vector requires local access and authentication, placing it within the context of lateral movement or initial persistence strategies where a low-privileged user seeks to gain higher-level control over the system. Unlike remote code execution vulnerabilities that can be triggered from an unauthenticated network position, this specific SSTP flaw necessitates that the attacker already possesses valid credentials on the target machine and must interact with the SSTP service directly, often through establishing a VPN connection or manipulating local configuration files depending on the exact trigger mechanism identified in detailed forensic analysis.
Mitigation strategies for this vulnerability primarily rely on applying vendor-provided security patches that address the input validation logic within the SSTP component. Organizations should ensure that all Windows systems are updated to versions containing the specific fix for this heap overflow issue. In environments where immediate patching is not feasible, network segmentation can help limit exposure by restricting access to services that interact with SSTP endpoints. Additionally, enforcing strict least-privilege policies ensures that even if an attacker successfully exploits this flaw, their ability to pivot or maintain persistence may be constrained by existing security controls such as User Account Control (UAC) and application whitelisting mechanisms designed to detect anomalous behavior associated with privilege escalation attempts.