CVE-2025-20776: 
NixOS vulnerability analysis and mitigation

CVE-2025-20776 is an out-of-bounds read vulnerability in the MediaTek display component, caused by a missing bounds check. It affects Android versions 14.0, 15.0, and 16.0 running on a wide range of MediaTek chipsets (including MT6739, MT6761, MT6765, MT6768, MT6781, MT6789, MT6833, MT6835, MT6853, MT6855, MT6877, MT6878, MT6879, MT6883, MT6885, MT6886, MT6889, MT6893, MT6895, MT6897, MT6899, MT6983, MT6985, MT6989, MT6991, and various MT8xxx series). The vulnerability was published on December 2, 2025, with a patch made available via MediaTek's December 2025 Product Security Bulletin (Patch ID: ALPS10184297; Issue ID: MSV-4759). It carries a CVSS v3.1 base score of 6.7 (Medium) (MediaTek Bulletin, Red Hat CVE).

The root cause is classified as CWE-125 (Out-of-bounds Read) — a missing bounds check in the display subsystem allows memory outside the intended buffer to be read. The attack vector is local, requiring the attacker to already possess System-level privileges on the affected device; no user interaction is required. Exploitation via this out-of-bounds read can lead to local privilege escalation beyond the System privilege level, potentially enabling full device compromise. No public proof-of-concept or detailed technical write-up has been identified at this time (MediaTek Bulletin).

Successful exploitation could allow a local attacker who already holds System privileges to escalate further, with high impact to confidentiality, integrity, and availability of the affected device. The vulnerability could enable unauthorized memory access, potentially exposing sensitive data or allowing persistent control over the device. Given the breadth of affected MediaTek chipsets across Android 14, 15, and 16, the scope of potentially vulnerable devices is significant (MediaTek Bulletin, Red Hat CVE).

There is no evidence of active in-the-wild exploitation or a publicly available proof-of-concept for CVE-2025-20776. The EPSS score is approximately 0.018% (0.000180), 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 the attacker to have already obtained System-level privileges on the target device, which significantly limits the attack surface (MediaTek Bulletin).

MediaTek has released a patch (Patch ID: ALPS10184297) addressed in the December 2025 Product Security Bulletin. Device manufacturers and OEMs should integrate and distribute this patch to affected devices running Android 14.0, 15.0, and 16.0 on impacted MediaTek chipsets. Lenovo has also published a corresponding advisory for affected MediaTek-based tablets. As interim mitigations, organizations should strictly limit and audit System-level access on affected devices, implement access controls to reduce the risk of privilege abuse, and monitor for unauthorized privilege escalation activity (MediaTek Bulletin, Lenovo Advisory).