CVE-2026-20433 Memory corruption in MediaTek chipset

High 8.8 Published 7 Apr 2026 Updated 8 Apr 2026

A missing bounds check in MediaTek modem firmware allows remote privilege escalation via a rogue base station, requiring user interaction.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-20433?

CVE-2026-20433 is a high-severity memory corruption vulnerability in MediaTek, Inc. MediaTek chipset, published on 7 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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: MOLY01088681; Issue ID: MSV-4460.

Weakness: CWE-787

Which versions are affected by CVE-2026-20433?

It affects 62 products.

Products include Mediatek Mt2735 Firmware, Mediatek Mt2737 Firmware, Mediatek Mt6813 Firmware, Mediatek Mt6833 Firmware, Mediatek Mt6833p Firmware, Mediatek Mt6835 Firmware and 56 more.

How do I fix CVE-2026-20433?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-20433 being exploited?

There is no known exploitation of CVE-2026-20433 in the wild and no public exploit code.

Sources

Also known as A-480745371, ASB-A-480745371, GHSA-5h6h-2wjp-jc72, M-MOLY01088681.