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critical advisory

Belkin F9K1122 Router Stack-Based Buffer Overflow Vulnerability

A stack-based buffer overflow vulnerability (CVE-2026-5042) exists in the Belkin F9K1122 router version 1.00.33, allowing remote attackers to execute arbitrary code by manipulating the webpage argument in the formCrossBandSwitch function.

A critical stack-based buffer overflow vulnerability, identified as CVE-2026-5042, has been discovered in Belkin F9K1122 routers running firmware version 1.00.33. The vulnerability resides within the formCrossBandSwitch function of the /goform/formCrossBandSwitch file, a component of the Parameter Handler. Successful exploitation could allow a remote, unauthenticated attacker to execute arbitrary code on the device. Publicly available exploit code increases the risk of widespread…

Detection coverage 2

Detect Suspiciously Long GET Request to formCrossBandSwitch

high

Detects unusually long GET requests to the /goform/formCrossBandSwitch endpoint, indicative of a buffer overflow attempt.

sigma tactics: exploitation techniques: T1210 sources: webserver, linux

Detect POST Request to formCrossBandSwitch with Long webpage Parameter

high

Detects unusually long POST requests to /goform/formCrossBandSwitch, indicative of CVE-2026-5042 exploitation.

sigma tactics: exploitation techniques: T1210 sources: webserver, linux

Detection queries are kept inside the platform. Get full rules →

Indicators of compromise

4

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