Netty has an IPv6 Subnet Filter Bypass via Incorrect Comparator Masking

Summary

An attacker can bypass IPv6 subnet rules due to an incorrect masking operation in IpSubnetFilterRule.compareTo(). Valid public IP addresses can bypass the restrictions.

Details

io.netty.handler.ipfilter.IpSubnetFilterRule#compareTo(java.net.InetSocketAddress) method performs a bitwise AND between the incoming IP address and the configured networkAddress, instead of the subnetMask.

Impact

Access Control Bypass. Attacker can bypass IpSubnetFilter IPv6 access controls.