CVE-2026-123957: Buffer Overflow in TOTOLINK CA300-PoE

CVE-2026-123957 is a buffer overflow in the setIpQosRules function of /cgi-bin/cstecgi.cgi on TOTOLINK CA300-PoE router version 6.2c.884. The vulnerability is triggered through manipulation of the ipStart argument and enables remote attack against affected devices. TOTOLINK CA300-PoE routers are common network devices in enterprise infrastructure and access environments, making this vulnerability a concrete risk to operations and security.

Severity is critical with CVSS 9.9 according to official data. The status is immediately concerning: the exploit has been publicly disclosed and no confirmed patched version exists yet. Social signals from November 7, 2026 show 3 posts in the last 24 hours with 34 total interactions, indicating active visibility and awareness already present among security teams. The device remains vulnerable until an official patch is distributed.

Administrators must act without delay: conduct immediate inventory of TOTOLINK CA300-PoE routers in use and document versions; verify the official TOTOLINK website and contact support for patch status; if an update is not immediately available, isolate routers from critical systems via network segmentation; completely disable remote access to the web administration interface if not strictly necessary; monitor traffic to these devices to detect exploitation attempts.