A stack-based buffer overflow vulnerability (CVE-2026-3715) was discovered in Wavlink WL-WN579X3-C router version 231124. The vulnerability affects the sub_40139C function in /cgi-bin/firewall.cgi through manipulation of the del_flag argument. The flaw can be exploited remotely and public exploits are available. The vendor has released a fixed version 20260226 to address this issue. Users are advised to upgrade immediately to mitigate the risk.