Quick answers
- Is CVE-2026-20540 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-20540 being exploited in the wild.
- How severe is CVE-2026-20540?
- Medium severity, with a CVSS score of 5.3, published 5 October 2026.
- Which products and versions are affected?
- MediaTek Dimensity 5G; MediaTek Helio 4G; MediaTek 5G Modems.
- Is there a fix for CVE-2026-20540?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-20540 attacked?
- It is attacked over the network, in device firmware.
- Am I affected by CVE-2026-20540?
- Check whether you run MediaTek 5G Modems, MediaTek Dimensity 5G or MediaTek Helio 4G. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An out of bounds read vulnerability exists in the Modem subcomponent due to missing bounds checking. The vulnerability can be triggered remotely when a user equipment (UE) connects to an attacker-controlled rogue base station, requiring no additional privileges or user interaction for exploitation. This results in remote denial of service.
Affected products
- MediaTek Dimensity 5G
- MediaTek Helio 4G
- MediaTek 5G Modems
Timeline
- 2026-10-05: disclosed