Infinite Loop Vulnerability in Linux Kernel IPv6 Implementation

CVE-2026-63969

What is CVE-2026-63969?

A vulnerability in the Linux kernel's IPv6 implementation can potentially lead to an infinite loop scenario in the function rt6_fill_node(). When writers hold the tb6_lock, they can execute list_del_rcu() on rt->fib6_siblings without waiting for RCU readers. This can cause a CPU stall as the next pointer in rt->fib6_siblings may reference an outdated structure. The issue is mitigated by ensuring that the rt->fib6_nsiblings is set to zero before executing the deletion, allowing for a reliable detach signal.

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