CVE-2026-64530

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

net/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle

tcf_classify() can return TC_ACT_CONSUMED while the skb is held by the

defragmentation engine (e.g. act_ct on out-of-order fragments). When

that happens the skb is no longer owned by the caller and must not be

touched again.

tcf_qevent_handle() did not handle TC_ACT_CONSUMED: it fell through the

switch and returned the skb to the caller as if classification had

passed. The only qdisc that wires up qevents today is RED, via three call sites

(qe_mark on RED_PROB_MARK/HARD_MARK, qe_early_drop on congestion_drop)

red_enqueue() was continuing to operate on an skb it no longer owns in this

case -- enqueueing it, dropping it, or updating statistics. Resulting in a UAF.

tc qdisc add dev eth0 root handle 1: red ... qevent early_drop block 10

tc filter add block 10 ... action ct

(with ct defrag enabled and traffic that produces out-of-order

fragments,

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References