Is CVE-2026-20504 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-20504 being exploited in the wild.

How severe is CVE-2026-20504?

Medium severity, with a CVSS score of 5.3, published 7 September 2026.

Which products and versions are affected?

MediaTek Modem MT2716, MT6835, MT6858, MT6878, MT6881, MT6897, MT6899, MT6982VB, MT6986, MT6988, MT6991, MT6993, MT8668, MT8676, MT8678, MT8755, MT8775, MT8792, MT8793, MT8863, MT8873, MT8883.

Is there a fix for CVE-2026-20504?

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-2026-20504 attacked?

It is attacked over the network, in device firmware.

Am I affected by CVE-2026-20504?

Check whether you run MediaTek Modem, MediaTek MT2735, MediaTek Mt2735 Firmware or one of the others listed at an affected version. 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.

CVE-2026-20504: MediaTek Modem denial of service due to missing bounds check

CVE-2026-20504 · Severity: medium · CVSS 5.3 · Published 2026-09-07

MediaTek modems are communication processors used in smartphones and IoT devices to handle cellular connectivity. A missing bounds check in the modem firmware can cause a system crash when a device connects to a rogue base station controlled by an attacker, resulting in service disruption. No special privileges or user interaction are required to exploit this vulnerability.

Quick answers

Is CVE-2026-20504 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-20504 being exploited in the wild.
How severe is CVE-2026-20504?: Medium severity, with a CVSS score of 5.3, published 7 September 2026.
Which products and versions are affected?: MediaTek Modem MT2716, MT6835, MT6858, MT6878, MT6881, MT6897, MT6899, MT6982VB, MT6986, MT6988, MT6991, MT6993, MT8668, MT8676, MT8678, MT8755, MT8775, MT8792, MT8793, MT8863, MT8873, MT8883.
Is there a fix for CVE-2026-20504?: 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-2026-20504 attacked?: It is attacked over the network, in device firmware.
Am I affected by CVE-2026-20504?: Check whether you run MediaTek Modem, MediaTek MT2735, MediaTek Mt2735 Firmware or one of the others listed at an affected version. 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

This vulnerability is a denial-of-service flaw caused by improper bounds checking in the modem subcomponent, allowing an out-of-bounds memory access or crash condition. The attack is triggered over the network when a user equipment (UE) connects to a malicious base station controlled by the attacker. The attacker sends specially crafted input that bypasses validation, causing the modem to crash and temporarily disabling cellular connectivity. No authentication or elevated privileges are required, and the attack succeeds without any user interaction. A patch is available (MOLY00755024).

Affected products

MediaTek Modem MT2716, MT6835, MT6858, MT6878, MT6881, MT6897, MT6899, MT6982VB, MT6986, MT6988, MT6991, MT6993, MT8668, MT8676, MT8678, MT8755, MT8775, MT8792, MT8793, MT8863, MT8873, MT8883

Timeline

2026-09-07: disclosed

References

https://www.mediatek.com/product-security-bulletin/September-2026

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