CVE-2025-38001 is a Use-After-Free vulnerability in the Linux network packet scheduler, specifically in the HFSC queuing discipline. When the HFSC qdisc is utilized with NETEM and NETEM packet duplication is enabled, using HFSC_RSC it is possible to cause a double class insertion in the HFSC eligible tree. Under normal conditions, this would lead to an infinite loop in hfsc_dequeue() due to an RBTree cycle. However, by adding TBF as root qdisc, it is possible to prevent packets from being dequeued, bypass the infinite loop, free the class, and trigger a Use-After-Free.