A stack-based buffer overflow vulnerability exists in the libshared.so library of Cisco Linksys E1200 v2 routers (Firmware E1200_v2.0.11.001_us.tar.gz). The functions get_mac_from_ip and get_ip_from_mac use sscanf with overly permissive "%100s" format specifiers to parse entries from /proc/net/arp into fixed-size buffers (v6: 50 bytes, v7 sub-arrays: 50 bytes). This allows local attackers controlling the contents of /proc/net/arp to overflow stack buffers, leading to memory corruption, denial of service, or potential arbitrary code execution.