Is CVE-2026-78862 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-78862 being exploited in the wild.

How severe is CVE-2026-78862?

Informational severity, published 5 October 2026.

Is there a fix for CVE-2026-78862?

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-2026-78862 attacked?

It is attacked with physical access.

Am I affected by CVE-2026-78862?

Check whether you run Mercusys AC12 V2. 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-2026-78862: Mercusys AC12 V2 arbitrary code execution via UART interface

CVE-2026-78862 · Severity: info · Published 2026-10-05

The Mercusys AC12 V2 is a Wi-Fi router sold to home and small office users. A local attacker with physical access to the device's circuit board can execute arbitrary code through an exposed UART serial interface, potentially gaining full control of the router and the networks it serves. An attacker would need to physically open the device and connect specialized hardware to the internal serial port.

Technologies: Mercusys AC12 V2. Vendors: Mercusys.

Quick answers

Is CVE-2026-78862 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-78862 being exploited in the wild.
How severe is CVE-2026-78862?: Informational severity, published 5 October 2026.
Which products and versions are affected?: Mercusys AC12 V2.
Is there a fix for CVE-2026-78862?: 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-2026-78862 attacked?: It is attacked with physical access.
Am I affected by CVE-2026-78862?: Check whether you run Mercusys AC12 V2. 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

The vulnerability allows arbitrary code execution via an exposed UART (Universal Asynchronous Receiver-Transmitter) serial interface on the device's PCB. This is a local physical attack vector requiring disassembly of the device and direct hardware access to the serial port. No information is provided about whether a patch exists or the exact nature of the code execution flaw.

Affected products

Mercusys AC12 V2

Timeline

2026-10-05: disclosed

References

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