CVE-2026-90250 bpf, cgroup: Fix storage null-ptr-deref after replacing prog
A local attacker can cause a kernel panic via null pointer dereference in BPF cgroup storage when replacing programs.
- 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-2026-90250?
CVE-2026-90250 is a vulnerability in Linux, published on 17 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:
bpf, cgroup: Fix storage null-ptr-deref after replacing prog
Syzkaller reported a storage null-ptr-deref issue after replacing prog. This occurs in the following scenario: 1. prog A, an empty prog, is attached to a cgrp. 2. prog B uses BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE and calls the bpf_get_local_storage helper. 3. link_update is called to replace prog A with prog B.
The reason is that __cgroup_bpf_replace fails to alloc and assign the required cgrp storage for the incoming replacement prog. Consequently, the new prog inherits an uninit storage, leading to null-ptr-deref panic when kick the new prog.
Fix this by rejecting a link update if new_prog's cgroup storage is incompatible with link->prog.
Which versions are affected by CVE-2026-90250?
How do I fix CVE-2026-90250?
Apply the vendor's patch.
Is CVE-2026-90250 being exploited?
There is no known exploitation of CVE-2026-90250 in the wild and no public exploit code.
Sources
Also known as AZL-102347, BELL-CVE-2026-90250, DEBIAN-CVE-2026-90250, GHSA-364x-ffh5-8mmx, UBUNTU-CVE-2026-90250.