CVE-2025-39773

/// Technical description

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

net: bridge: fix soft lockup in br_multicast_query_expired()

When set multicast_query_interval to a large value, the local variable

'time' in br_multicast_send_query() may overflow. If the time is smaller

than jiffies, the timer will expire immediately, and then call mod_timer()

again, which creates a loop and may trigger the following soft lockup

issue.

watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66]

CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none)

Call Trace:

<IRQ>

__netdev_alloc_skb+0x2e/0x3a0

br_ip6_multicast_alloc_query+0x212/0x1b70

__br_multicast_send_query+0x376/0xac0

br_multicast_send_query+0x299/0x510

br_multicast_query_expired.constprop.0+0x16d/0x1b0

call_timer_fn+0x3b/0x2a0

__run_timers+0x619/0x950

run_timer_softirq+0x11c/0x220

handle_softirqs+0x18e/0x560

__irq_exit_rcu+0x158/0x1a0

sysvec_apic_timer_interrupt+0x76/

/// 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