Linux Kernel Vulnerability in Netfilter Multiport Feature

CVE-2026-31681

What is CVE-2026-31681?

A vulnerability in the Linux kernel's netfilter component allows for improper validation of port range encoding within multiport rules. The ports_match_v1() function fails to adequately check the legitimacy of given port ranges, leading to potential exploitation through malformed rules that can misinterpret the intended port range logic. This oversight allows for scenarios where rules may be constructed in such a way that they bypass expected validations, risking the robustness of network security configurations.

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