CVE-2026-20520 Memory corruption in MediaTek chipset

High 7.5 Published 5 Oct 2026 Updated 6 Oct 2026

A missing bounds check in MediaTek modem firmware allows remote privilege escalation via a rogue base station without user interaction.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-20520?

CVE-2026-20520 is a high-severity memory corruption vulnerability in MediaTek, Inc. MediaTek chipset, published on 5 Oct 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 not needed for exploitation. Patch ID: MOLY01778988; Issue ID: MSV-8897.

Weakness: CWE-787

Which versions are affected by CVE-2026-20520?

It affects 57 products.

Products include Mediatek Mt2716 Firmware, Mediatek Mt2735 Firmware, Mediatek Mt2737 Firmware, Mediatek Mt6813 Firmware, Mediatek Mt6815 Firmware, Mediatek Mt6833 Firmware and 51 more.

How do I fix CVE-2026-20520?

No fix has been published for CVE-2026-20520 yet. Limit exposure of the affected software until one is available.

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

Is CVE-2026-20520 being exploited?

There is no known exploitation of CVE-2026-20520 in the wild and no public exploit code.

Sources

Also known as GHSA-w557-6g77-vqj5.