CVE-2026-90250

/// Technical 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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References