CVE-2026-22999 net/sched: sch_qfq: do not free existing class in qfq_change_class()
A use-after-free vulnerability in the Linux kernel's QFQ scheduler allows attackers to potentially execute code or escalate privileges.
- 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-2026-22999?
CVE-2026-22999 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jan 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: sch_qfq: do not free existing class in qfq_change_class()
Fixes qfq_change_class() error case.
cl->qdisc and cl should only be freed if a new class and qdisc were allocated, or we risk various UAF.
Weakness: CWE-416
Which versions are affected by CVE-2026-22999?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-22999?
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-2026-22999 being exploited?
There is no known exploitation of CVE-2026-22999 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-77133, AZL-78485, BELL-CVE-2026-22999, DEBIAN-CVE-2026-22999, GHSA-3phq-r8q7-gf9j, ROOT-OS-DEBIAN-11-CVE-2026-22999 and 5 more.