CVE-2026-78862

MEDIUM

Published Oct 5, 2026 Modified Oct 6, 2026 CWE-1299

Description

An issue in Mercusys AC12 V2 allows a local attacker to execute arbitrary code via the UART serial interface on the printed circuit board (PCB)

Is your site exposed to CVE-2026-78862?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

6.8

MEDIUM

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0026

Probability of exploitation

0.18%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1299 CWE-1299

References

Other References

http://ac12.com http://mercusys.com https://threadpoolx.gitbook.io/docs/cve/mercusys-ac12-v2-security-advisory/unprotected-physical-debug-interface-uart https://threadpoolx.gitbook.io/docs/cve/mercusys-ac12-v2-security-advisory/unprotected-physical-debug-interface-uart

Frequently Asked Questions

What is CVE-2026-78862? +

An issue in Mercusys AC12 V2 allows a local attacker to execute arbitrary code via the UART serial interface on the printed circuit board (PCB) It has a CVSS v3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-78862? +

CVE-2026-78862 has a CVSS v3.1 score of 6.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0026, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-78862? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-53699

Missing protection mechanism for alternate hardware interface vulnerability in Johnson Controls iSTAR Ultra, Johnson Controls iSTAR Ultra SE, Johnson Controls …

CVE-2025-53698

Missing protection mechanism for alternate hardware interface vulnerability in Johnson Controls iSTAR Ultra and Johnson Controls iSTAR Ultra SE allows …

CVE-2025-1073 7.5

Panasonic IR Control Hub (IR Blaster) versions 1.17 and earlier may allow an attacker with physical access to load unauthorized …

CVE-2025-41697 6.8

An attacker can use an undocumented UART port on the PCB as a side-channel to get root access e.g. with …

CVE-2025-26409 6.8

A serial interface can be accessed with physical access to the PCB of Wattsense Bridge devices. After connecting to the …

CVE-2024-47944 6.8

The device directly executes .patch firmware upgrade files on a USB stick without any prior authentication in the admin interface. …