CVE-2026-72323

/// Technical description

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

ipv4: igmp: Fix potential UAF in igmp_gq_start_timer()

A race condition exists between device teardown (inetdev_destroy) and

incoming IGMP query processing (igmp_rcv), leading to a Use-After-Free

in the IGMP timer callback.

During device destruction, inetdev_destroy() drops the primary reference

to in_device, which can drop its refcount to 0. The actual freeing of

in_device memory is deferred via RCU (using call_rcu()).

Concurrently, igmp_rcv() runs under RCU read lock and obtains the

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

dereference in_device even if its refcount has hit 0.

However, if CPU-0 calls igmp_gq_start_timer() and re-arms the timer, it

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

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

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

grace period (as the

/// 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