CVE-2026-64207 net/sched: dualpi2: fix GSO backlog accounting
A NULL pointer dereference in the Linux kernel's DualPI2 scheduler can cause a system crash when processing GSO packets with QFQ as the parent.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64207?
CVE-2026-64207 is a medium-severity vulnerability in Linux kernel, published on 20 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net/sched: dualpi2: fix GSO backlog accounting
When DualPI2 splits a GSO skb into N segments, it propagates N additional packets to its parent before returning NET_XMIT_SUCCESS. The parent then accounts for the original skb once more, leaving its qlen one larger than the number of packets actually queued.
With QFQ as the parent, after all real packets are dequeued, QFQ still has a non-zero qlen while its in-service aggregate has no active classes. qfq_choose_next_agg() returns NULL and qfq_dequeue() passes the result to qfq_peek_skb(), causing a NULL pointer dereference.
Follow the same pattern used by tbf_segment() and taprio: count only successfully queued segments, propagate the difference between the original skb and those segments, and return NET_XMIT_SUCCESS whenever at least one segment was queued.
Weakness: CWE-476
Which versions are affected by CVE-2026-64207?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64207?
Apply the vendor's patch.
Is CVE-2026-64207 being exploited?
There is no known exploitation of CVE-2026-64207 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64207, DEBIAN-CVE-2026-64207, GHSA-mghj-w558-vm84, UBUNTU-CVE-2026-64207.