CVE-2026-98383 bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL
A use-after-free vulnerability in the Linux kernel BPF subsystem allows local attackers with high privileges to execute arbitrary code or escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98383?
CVE-2026-98383 is a high-severity use after free vulnerability in Linux, published on 9 Oct 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:
bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL
An LWT_SEG6LOCAL program can invalidate its cached SRH with bpf_lwt_seg6_adjust_srh() and then call bpf_skb_pull_data(). The latter may reallocate skb->head, leaving the per-CPU SRH pointer dangling. Post-program SRH validation then writes through that pointer.
Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL programs so the verifier rejects this unsafe helper combination. Other LWT program types continue to expose the helper through lwt_out_func_proto().
Which versions are affected by CVE-2026-98383?
How do I fix CVE-2026-98383?
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-2026-98383 being exploited?
There is no known exploitation of CVE-2026-98383 in the wild and no public exploit code.
Sources
Also known as AZL-106899, BELL-CVE-2026-98383, DEBIAN-CVE-2026-98383, GHSA-ph4x-4wh2-2qrm, UBUNTU-CVE-2026-98383.