CVE-2025-20788: 
NixOS vulnerability analysis and mitigation

CVE-2025-20788 is a memory corruption vulnerability in the GPU PDMA (Physical Direct Memory Access) component of MediaTek chipsets, caused by a missing permission check. It affects Android 15.0 devices running on MediaTek MT6991 and MT8196 chipsets. Successful exploitation could lead to local denial of service. The vulnerability was published on December 2, 2025, with a patch released in MediaTek's December 2025 Product Security Bulletin (Patch ID: ALPS10117735; Issue ID: MSV-4539). It carries a CVSS v3.1 base score of 4.4 (Medium) (MediaTek Bulletin, Red Hat CVE).

The root cause is classified as CWE-1262 (Improper Access Control for Register Interface), specifically a missing permission check in the GPU PDMA subsystem that allows unauthorized memory operations. An attacker with local access can trigger memory corruption without requiring additional execution privileges, though user interaction is required for exploitation. The attack vector is local (AV:L), meaning the attacker must have physical or logical access to the device, and must induce a user to perform some action (e.g., open a malicious application) to trigger the flaw (MediaTek Bulletin).

Exploitation of this vulnerability can result in a local denial of service condition on affected Android 15.0 devices, with limited impact on system integrity and availability. Confidentiality is not affected, but the memory corruption could cause system instability or crashes. The scope is limited to the affected device and does not enable privilege escalation or remote code execution based on current analysis (MediaTek Bulletin, Red Hat CVE).

There is no known public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time. The EPSS score is approximately 0.018%, indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires local access and user interaction, which further limits the practical attack surface (MediaTek Bulletin).

MediaTek has released a patch (Patch ID: ALPS10117735) for affected Android 15.0 devices with MT6991 and MT8196 chipsets, available through the December 2025 MediaTek Product Security Bulletin. Device manufacturers such as Lenovo have also issued advisories for affected tablet products. Users should apply the latest OEM security updates as soon as they are available, restrict physical and local access to devices, and avoid installing untrusted applications (MediaTek Bulletin, Lenovo Advisory).

Red Hat has tracked this CVE in their security database, and Lenovo issued a product security advisory for affected MediaTek-based tablets. No significant researcher commentary or broad media coverage has been identified for this vulnerability, consistent with its medium severity and limited exploitation potential (Red Hat CVE, Lenovo Advisory).