Linux Kernel Vulnerability Affecting Network Socket Handling

CVE-2026-80733

What is CVE-2026-80733?

A flaw in the Linux kernel's socket handling can lead to improper processing of non-INET socket types, such as AF_PACKET sockets. Specifically, the function sk_mc_loop() may trigger a warning when it encounters socket families that are not AF_INET or AF_INET6. This occurs when sending packets via raw/packet sockets over virtual devices like VRF or ipvlan, causing sk_mc_loop() to erroneously invoke WARN_ON_ONCE(1). Since non-INET sockets do not support multicast loopback options, the expected behavior should be to default loopback to true without raising unnecessary warnings.

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