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CVE-2021-35406 is a command injection vulnerability in the Prolink PRC2402M router, tested on firmware version 20190909. Based on the provided supporting content, the flaw is in the /cgi-bin/qos.cgi CGI handler. When the page parameter is set to qos, the qos_settings routine processes attacker-controlled parameters including qos_dat and qos_bandwidth, uses sprintf to embed them into shell command strings, and executes the resulting command via do_system, a wrapper around system, without sufficient input validation or sanitization. This allows arbitrary shell metacharacters or command substitution to be injected through HTTP POST parameters. The provided proof of concept uses a crafted POST request to /cgi-bin/qos.cgi with page=qos and a malicious qos_dat value such as $(echo gg>/tmp/gg) to demonstrate code execution.
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No public exploit code observed for this vulnerability.
3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A command injection vulnerability affecting the PROLiNK PRC2402M router.
An authenticated command injection vulnerability in the Prolink PRC2402M router that allows arbitrary code execution as root via unsanitized user input passed to system().
An unauthenticated command injection vulnerability in the Prolink PRC2402M router's qos.cgi endpoint that allows arbitrary code execution as root.
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Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.