CVE-2026-72322

Technical Description

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

ipv6: mcast: Fix potential UAF in MLD delayed work

A race condition exists between device teardown and incoming MLD query

processing, leading to a Use-After-Free in the MLD delayed work.

During device destruction, the primary reference to inet6_dev is dropped,

which can drop its refcount to 0. The actual freeing of inet6_dev memory

is deferred via RCU.

Concurrently, the packet receive path runs under RCU read lock and obtains

the inet6_dev pointer. Because the memory is RCU-protected, CPU-0 can

safely dereference inet6_dev even if its refcount has hit 0.

However, if CPU-0 calls igmp6_event_query() and schedules delayed work, it

attempts to acquire a reference using in6_dev_hold(). This increments the

refcount from 0 to 1, triggering a "refcount_t: addition on 0" warning.

Since the inet6_dev memory is still scheduled to be freed after the RCU

grace period, the device is freed while the work is still scheduled.

When

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