CVE-2026-69874 in Windows
Summary
by MITRE • 09/09/2026
Untrusted pointer dereference in Windows ALPC allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described involves an untrusted pointer dereception within the Local Procedure Call (ALPC) mechanism of Microsoft Windows, a critical component responsible for inter-process communication on NT-based operating systems. This flaw represents a significant security risk as it allows an authorized attacker to escalate privileges from a lower-privileged user account to that of SYSTEM or another high-level process. The ALPC subsystem is deeply integrated into the kernel and handles numerous system-critical communications, making any instability or logical error within its pointer handling logic particularly dangerous. When the operating system processes messages sent via ALPC, it relies on pointers provided by the calling application to locate data structures in memory. If these pointers are not rigorously validated against trusted bounds before being dereferenced, an attacker can manipulate them to point to arbitrary kernel-mode addresses or sensitive user-space regions that should be inaccessible.
The technical root cause lies in insufficient validation of input parameters passed through the ALPC interface. Specifically, when a process sends a message containing pointer-based data structures, the receiving end, often handled by system services running with elevated privileges, fails to verify that these pointers are valid and reside within an expected memory range accessible to the sender or intended for kernel processing. This lack of boundary checking enables what is known as a type confusion or arbitrary write primitive if combined with other conditions, but in this specific context, it primarily facilitates privilege escalation by allowing the attacker to corrupt kernel data structures or redirect execution flow. By carefully crafting malicious ALPC messages, an authenticated user can trick the system into dereferencing pointers that lead to unintended memory locations, potentially overwriting critical control structures such as access tokens or security descriptors associated with higher-privileged processes.
From a threat modeling perspective, this vulnerability aligns closely with CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer and more specifically CWE-824 Access of Uninitialized Pointer in some variations where invalid pointers are used due to lack of initialization checks during ALPC message parsing. In terms of adversary behavior, it maps directly to MITRE ATT&CK technique T1068 Exploitation for Privilege Escalation. Attackers typically leverage this flaw after gaining initial access through phishing, malware infection, or other entry points that provide standard user-level credentials. Once inside the system with limited permissions, they execute a local exploit utilizing the ALPC vulnerability to bypass security boundaries and gain administrative control. This capability is particularly concerning because it does not require physical access or hardware exploits, relying solely on software logic errors within the OS kernel components.
The operational impact of this flaw extends beyond simple privilege escalation. An attacker with SYSTEM-level privileges can install rootkits, disable security monitoring tools like Windows Defender, modify registry keys to establish persistence mechanisms, and exfiltrate sensitive data without detection. Furthermore, because ALPC is used by many core system services including the Service Control Manager and various authentication subsystems, exploiting this vulnerability may destabilize the entire operating system if the memory corruption leads to a bug check or blue screen of death. This instability can be weaponized for denial-of-service attacks even when privilege escalation fails, although successful exploitation primarily targets confidentiality and integrity violations through unauthorized administrative access.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Microsoft has addressed this issue in subsequent security updates, so applying the latest cumulative patches is the primary defense vector. Organizations should ensure that their Windows endpoints are configured to automatically download and install critical security fixes within a defined timeframe to minimize exposure windows. Additionally, implementing application whitelisting policies can prevent unauthorized executables from running ALPC calls with malicious payloads. For environments where patching cannot be immediate immediately deployed, network segmentation limits the lateral movement potential if an attacker gains initial foothold via other means. Security teams should also monitor for anomalous process creation events involving system services communicating over local ports, as such activity may indicate exploitation attempts in progress using tools like Metasploit or custom-built exploits targeting this specific ALPC flaw.