CVE-2026-98017 net/sched: defer qdisc freeing after failed creation
A use-after-free in the Linux kernel network scheduler allows attackers to cause denial of service or execute code via crafted RTM_NEWQDISC requests.
- 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-2026-98017?
CVE-2026-98017 is a high-severity use after free vulnerability in Linux, published on 25 Sep 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: defer qdisc freeing after failed creation
An RTM_NEWQDISC request can make clsact bind a populated shared ingress block during ->init(), publishing an embedded mini_Qdisc to lockless readers. If the same request has an invalid TCA_RATE, estimator setup fails after ->init(); the unwind removes the pointer but synchronously frees its containing qdisc while tc_run() may still hold it.
Retire failed qdiscs through the same RCU helper as normal destruction. Inline the synchronous free into the callback now that no direct callers remain.
Which versions are affected by CVE-2026-98017?
How do I fix CVE-2026-98017?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98017 being exploited?
There is no known exploitation of CVE-2026-98017 in the wild and no public exploit code.
Sources
Also known as AZL-104457, BELL-CVE-2026-98017, DEBIAN-CVE-2026-98017, GHSA-wjw6-9w8q-rvjv, UBUNTU-CVE-2026-98017.