CVE-2026-20479 Denial of service in MediaTek chipset

High 7.5 Published 3 Aug 2026 Updated 3 Aug 2026

A missing bounds check in MediaTek modem firmware allows remote attackers to cause denial of service via a rogue base station.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-20479?

CVE-2026-20479 is a high-severity denial of service vulnerability in MediaTek, Inc. MediaTek chipset, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

In Modem, there is a possible out of bounds read due to a missing bounds check. This could lead to remote denial of service, 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: MOLY00741071; Issue ID: MSV-7620.

Weakness: CWE-125

Which versions are affected by CVE-2026-20479?

It affects 19 products.

Products include Mediatek Mt2735 Firmware, Mediatek Mt6833 Firmware, Mediatek Mt6853 Firmware, Mediatek Mt6855 Firmware, Mediatek Mt6873 Firmware, Mediatek Mt6875 Firmware and 13 more.

How do I fix CVE-2026-20479?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-20479 being exploited?

There is no known exploitation of CVE-2026-20479 in the wild and no public exploit code.

Sources

Also known as A-518610755, ASB-A-518610755, GHSA-6g35-p5gh-6qh4, M-MOLY00741071.