CVE-2026-45966

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

apparmor: fix NULL pointer dereference in __unix_needs_revalidation

When receiving file descriptors via SCM_RIGHTS, both the socket pointer

and the socket's sk pointer can be NULL during socket setup or teardown,

causing NULL pointer dereferences in __unix_needs_revalidation().

This is a regression in AppArmor 5.0.0 (kernel 6.17+) where the new

__unix_needs_revalidation() function was added without proper NULL checks.

The crash manifests as:

BUG: kernel NULL pointer dereference, address: 0x0000000000000018

RIP: aa_file_perm+0xb7/0x3b0 (or +0xbe/0x3b0, +0xc0/0x3e0)

Call Trace:

apparmor_file_receive+0x42/0x80

security_file_receive+0x2e/0x50

receive_fd+0x1d/0xf0

scm_detach_fds+0xad/0x1c0

The function dereferences sock->sk->sk_family without checking if either

sock or sock->sk is NULL first.

Add NULL checks for both sock and sock->sk before accessing sk_family.

/// 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