CVE-2026-44249

Netty is a network application framework for development of protocol servers and clients. In netty-handler prior to versions 4.1.135.Final and 4.2.15.Final, an attacker can bypass IPv6 subnet rules due to an incorrect masking operation in IpSubnetFilterRule.compareTo(). Valid public IP addresses can bypass the restrictions. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Netty is a network application framework for development of protocol servers and clients. In netty-handler prior to versions 4.1.135.Final and 4.2.15.Final, an attacker can bypass IPv6 subnet rules due to an incorrect masking operation in IpSubnetFilterRule.compareTo(). Valid public IP addresses can bypass the restrictions. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

### 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.

### 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.