CVE-2025-39773

EUVD-2025-28939
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+0x76/0x90
   </IRQ>

This issue can be reproduced with:
  ip link add br0 type bridge
  echo 1 > /sys/class/net/br0/bridge/multicast_querier
  echo 0xffffffffffffffff >
  	/sys/class/net/br0/bridge/multicast_query_interval
  ip link set dev br0 up

The multicast_startup_query_interval can also cause this issue. Similar to
the commit 99b40610956a ("net: bridge: mcast: add and enforce query
interval minimum"), add check for the query interval maximum to fix this
issue.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.5 MEDIUM
LOCAL
LOW
LOW
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 1%
Affected Products (NVD)
VendorProductVersion
linuxlinux_kernel
2.6.34 ≤
𝑥
< 5.15.190
linuxlinux_kernel
5.16 ≤
𝑥
< 6.1.149
linuxlinux_kernel
6.2 ≤
𝑥
< 6.6.103
linuxlinux_kernel
6.7 ≤
𝑥
< 6.12.44
linuxlinux_kernel
6.13 ≤
𝑥
< 6.16.4
linuxlinux_kernel
6.17:rc1
linuxlinux_kernel
6.17:rc2
debiandebian_linux
11.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
linux
bookworm
6.1.159-1
fixed
bookworm (security)
6.1.162-1
fixed
bullseye
vulnerable
bullseye (security)
vulnerable
forky
6.18.9-1
fixed
sid
6.18.12-1
fixed
trixie
6.12.63-1
fixed
trixie (security)
6.12.73-1
fixed
linux-6.1
bullseye (security)
6.1.162-1~deb11u1
fixed