CVE-2026-64530

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

net/sched: clsapi: Handle TCACTCONSUMED in tcfqevent_handle

tcfclassify() can return TCACT_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.

tcfqeventhandle() did not handle TCACTCONSUMED: 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

(qemark on REDPROBMARK/HARDMARK, qeearlydrop 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, e.g. a fragmented UDP stream)

Handle TCACTCONSUMED in tcfqeventhandle() the same way the ingress

and egress fast paths do: treat it as stolen and return NULL without

touching the skb. Unlike the TCACTSTOLEN case, the skb must not be

dropped/freed here, as it is no longer owned by us.