Quick answers
- Is CVE-2026-20557 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-20557 being exploited in the wild.
- How severe is CVE-2026-20557?
- Informational severity, published 2 November 2026.
- Which products and versions are affected?
- MediaTek Modem firmware.
- Is there a fix for CVE-2026-20557?
- 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-2026-20557 attacked?
- It is attacked over the network or from the adjacent network, in device firmware.
- Am I affected by CVE-2026-20557?
- Check whether you run MediaTek Modem firmware. 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 write vulnerability exists in MediaTek modem firmware due to insufficient bounds checking. The vulnerability can be triggered remotely when a user equipment (UE) connects to a rogue base station controlled by an attacker, requiring no additional privileges. Successful exploitation results in privilege escalation on the affected device.
Affected products
- MediaTek Modem firmware
Timeline
- 2026-11-02: disclosed