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Command Injection in Totolink A3300R setLanCfg
CVE-2026-5101 is a command injection vulnerability affecting Totolink A3300R firmware version 17.0.0cu.557_b20221024. The flaw is in the setLanCfg function exposed through /cgi-bin/cstecgi.cgi in the Parameter Handler component. According to the provided information, improper handling of the lanIp argument allows attacker-controlled input to be interpreted by the underlying system in a way that results in OS command injection. The issue is remotely exploitable, and public exploit code is reported to be available.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation can allow a remote attacker to execute arbitrary system commands in the context of the vulnerable device's web management process. Based on the supplied record, this can result in compromise of confidentiality, integrity, and availability on the affected router, including unauthorized configuration changes, access to sensitive device data, service disruption, and likely broader device takeover depending on the privileges of the affected process.
If you can’t patch tonight, do this now.
Restrict access to the router management interface and /cgi-bin/cstecgi.cgi to trusted administrative networks only. Disable remote administration from untrusted networks, place the device behind firewall rules or ACLs, and ensure the management plane is not exposed to the Internet. Monitor for suspicious requests involving the lanIp parameter and signs of command execution on the device. If patching is unavailable, consider removing the device from exposed environments or replacing it with supported hardware.
Patch, then assume compromise.
Upgrade Totolink A3300R firmware to a vendor-fixed version if one is available. Because the vulnerable behavior is tied to improper handling of the lanIp parameter in setLanCfg within /cgi-bin/cstecgi.cgi, remediation should include vendor changes that eliminate command injection by removing shell invocation where possible, strictly validating and canonicalizing input, and safely passing parameters to system APIs. If no fixed firmware has been published, the information is currently not available beyond replacing or isolating the affected device.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.