NULL Pointer Dereference Affecting linux-azure-6.18 package, versions <6.18.31-r0


Severity

Recommended
0.0
medium
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
0.16% (5th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-CHAINGUARDLATEST-LINUXAZURE618-16727189
  • published17 May 2026
  • disclosed24 Apr 2026

Introduced: 24 Apr 2026

CVE-2026-31579  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade Chainguard linux-azure-6.18 to version 6.18.31-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-azure-6.18 package and not the linux-azure-6.18 package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

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

wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit

wg_netns_pre_exit() manually acquires rtnl_lock() inside the pernet .pre_exit callback. This causes a hung task when another thread holds rtnl_mutex - the cleanup_net workqueue (or the setup_net failure rollback path) blocks indefinitely in wg_netns_pre_exit() waiting to acquire the lock.

Convert to .exit_rtnl, introduced in commit 7a60d91c690b ("net: Add ->exit_rtnl() hook to struct pernet_operations."), where the framework already holds RTNL and batches all callbacks under a single rtnl_lock()/rtnl_unlock() pair, eliminating the contention window.

The rcu_assign_pointer(wg->creating_net, NULL) is safe to move from .pre_exit to .exit_rtnl (which runs after synchronize_rcu()) because all RCU readers of creating_net either use maybe_get_net()

  • which returns NULL for a dying namespace with zero refcount - or access net->user_ns which remains valid throughout the entire ops_undo_list sequence.

[ Jason: added __net_exit and __read_mostly annotations that were missing. ]

CVSS Base Scores

version 3.1