Out-of-bounds write in MediaTek Modem firmware leads to privilege escalation
CVE-2026-20434 Published on March 2, 2026

In Modem, there is a possible out of bounds write due to a missing bounds check. This could lead to remote escalation of privilege, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is needed for exploitation. Patch ID: MOLY00782946; Issue ID: MSV-4135.

NVD

Vulnerability Analysis

Attack Vector:
ADJACENT_NETWORK
Attack Complexity:
HIGH
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH

Weakness Type

What is a Memory Corruption Vulnerability?

The software writes data past the end, or before the beginning, of the intended buffer. Typically, this can result in corruption of data, a crash, or code execution. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent write operation then produces undefined or unexpected results.

CVE-2026-20434 has been classified to as a Memory Corruption vulnerability or weakness.


Products Associated with CVE-2026-20434

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MediaTek Mt6989
 

Affected Versions

MediaTek, Inc. MT2735, MT2737, MT6739, MT6761, MT6762, MT6762D, MT6762M, MT6763, MT6765, MT6765T, MT6767, MT6768, MT6769, MT6769K, MT6769S, MT6769T, MT6769Z, MT6771, MT6779, MT6781, MT6783, MT6785, MT6785T, MT6785U, MT6789, MT6833, MT6833P, MT6835, MT6835T, MT6853, MT6853T, MT6855, MT6855T, MT6873, MT6875, MT6875T, MT6877, MT6877T, MT6877TT, MT6878, MT6878M, MT6879, MT6880, MT6883, MT6885, MT6886, MT6889, MT6890, MT6891, MT6893, MT6895, MT6895TT, MT6896, MT6897, MT6899, MT6980, MT6980D, MT6983, MT6983T, MT6985, MT6985T, MT6989, MT6989T, MT6990, MT6991, MT8666, MT8667, MT8668, MT8673, MT8675, MT8676, MT8678, MT8755, MT8765, MT8766, MT8766R, MT8768, MT8771, MT8781, MT8786, MT8788, MT8788E, MT8789, MT8791, MT8791T, MT8792, MT8793, MT8795T, MT8797, MT8798, MT8863, MT8873, MT8883, MT8893 Version Modem LR12A, LR13, NR15, NR16, NR17 is affected by CVE-2026-20434

Exploit Probability

EPSS
0.06%
Percentile
19.48%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.