CVE-2026-20559 in MT6993
Summary
by MITRE • 11/02/2026
In GPU pdma, there is a possible memory corruption due to use after free. This could lead to local escalation of privilege with User execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS11365081; Issue ID: MSV-9545.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability identified under issue identifier MSV-9545 and addressed by patch ALPS11365081 resides within the peripheral direct memory access controller, commonly referred to as pdma, of a graphics processing unit architecture. This component is responsible for managing data transfers between system memory and GPU hardware without continuous intervention from the central processor. The core technical flaw involves a use-after-free condition, which constitutes a critical class of memory safety violations where software continues to reference a block of memory after it has been freed or deallocated by the system. In this specific context, the pdma subsystem fails to properly invalidate pointers or update state management structures when resources are released, allowing subsequent operations to access stale memory addresses that may have been reallocated for different purposes.
From a technical perspective, use-after-free vulnerabilities arise due to improper lifecycle management of dynamic memory allocations within kernel-space drivers or firmware components. When the pdma controller releases a buffer descriptor or control structure but retains an active reference to it in its internal queues or state machines, any subsequent operation that triggers access to this dangling pointer can lead to unpredictable behavior. If the operating system has reallocated that freed memory region for another process or kernel object, writing to or reading from the stale address allows an attacker to manipulate data belonging to unrelated entities. This mechanism bypasses standard isolation boundaries because the pdma operates at a low level with direct hardware access capabilities, effectively granting the malicious code elevated privileges through legitimate system pathways rather than exploiting external attack vectors.
The operational impact of this vulnerability is severe due to its potential for local privilege escalation. An attacker who achieves user-level execution on the affected device can exploit this flaw to gain higher-privilege access, potentially reaching kernel or root levels depending on the specific implementation details of the pdma driver and operating system security model. The requirement for only User execution privileges makes exploitation significantly more feasible compared to vulnerabilities requiring administrative rights initially. Furthermore, the fact that user interaction is not needed for exploitation means that an attacker does not require social engineering tactics such as tricking a victim into clicking a link or opening a file; instead, the vulnerability can be triggered automatically by background processes, scripts, or malicious applications running in isolation within the user space environment.
This type of memory corruption aligns with Common Weakness Enumeration identifier CWE-416, which specifically categorizes use-after-free errors as dangerous programming mistakes that lead to undefined behavior and potential security breaches. In terms of offensive cybersecurity frameworks, this vulnerability maps closely to techniques found in the MITRE ATT&CK catalog related to privilege escalation via memory corruption or driver exploitation. Attackers typically leverage such flaws to inject shellcode into kernel space, hijack control flow execution paths, or corrupt critical data structures like access control lists and security tokens. The absence of user interaction further classifies this as a high-severity issue because it reduces the attack surface complexity and increases the likelihood of successful automated exploitation in multi-tenant environments or devices with persistent background services.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Applying the vendor-provided patch ALPS11365081 is the primary remediation step, as it likely includes fixes to properly nullify pointers after deallocation, add reference counting mechanisms to prevent premature freeing of resources, or implement bounds checking within the pdma driver logic. Beyond software updates, developers should enforce strict memory safety practices such as using static analysis tools during code review to detect dangling pointer usage early in the development lifecycle. Additionally, enabling hardware-enforced security features like kernel address space layout randomization and full RELRO can mitigate exploitation attempts by making it harder for attackers to predict memory layouts or overwrite critical function pointers. Regular auditing of driver code against CWE-416 patterns will help prevent similar vulnerabilities from being introduced in future releases.