{"id":"CVE-2025-39773","title":"net: bridge: fix soft lockup in br_multicast_query_expired()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: fix soft lockup in br_multicast_query_expired()\n\nWhen set multicast_query_interval to a large value, the local variable\n'time' in br_multicast_send_query()…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 34171b9e53bd1dc264f5556579f2b04f04435c73","Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 43e281fde5e76a866a4d10780c35023f16c0e432","Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 96476b043efb86a94f2badd260f7f99c97bd5893","Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < bdb19cd0de739870bb3494c815138b9dc30875c4","Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 5bf5fce8a0c2a70d063af778fdb5b27238174cdd","Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < d1547bf460baec718b3398365f8de33d25c5f36f","Linux 2.6.34"],"published":"2025-09-11","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:42:17.113Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-39773","references":[{"url":"https://git.kernel.org/stable/c/34171b9e53bd1dc264f5556579f2b04f04435c73"},{"url":"https://git.kernel.org/stable/c/43e281fde5e76a866a4d10780c35023f16c0e432"},{"url":"https://git.kernel.org/stable/c/96476b043efb86a94f2badd260f7f99c97bd5893"},{"url":"https://git.kernel.org/stable/c/bdb19cd0de739870bb3494c815138b9dc30875c4"},{"url":"https://git.kernel.org/stable/c/5bf5fce8a0c2a70d063af778fdb5b27238174cdd"},{"url":"https://git.kernel.org/stable/c/d1547bf460baec718b3398365f8de33d25c5f36f"}],"tags":["cve.org"],"epss":0.0012,"epssPercentile":0.02056,"ingestedAt":"2026-09-08T15:33:26.997Z","slug":"CVE-2025-39773","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: fix soft lockup in br_multicast_query_expired()\n\nWhen set multicast_query_interval to a large value, the local variable\n'time' in br_multicast_send_query() may overflow. If the time is smaller\nthan jiffies, the timer will expire immediately, and then call mod_timer()\nagain, which creates a loop and may trigger the following soft lockup\nissue.\n\n  watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66]\n  CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none)\n  Call Trace:\n   <IRQ>\n   __netdev_alloc_skb+0x2e/0x3a0\n   br_ip6_multicast_alloc_query+0x212/0x1b70\n   __br_multicast_send_query+0x376/0xac0\n   br_multicast_send_query+0x299/0x510\n   br_multicast_query_expired.constprop.0+0x16d/0x1b0\n   call_timer_fn+0x3b/0x2a0\n   __run_timers+0x619/0x950\n   run_timer_softirq+0x11c/0x220\n   handle_softirqs+0x18e/0x560\n   __irq_exit_rcu+0x158/0x1a0\n   sysvec_apic_timer_interrupt+0x76/0x90\n   </IRQ>\n\nThis issue can be reproduced with:\n  ip link add br0 type bridge\n  echo 1 > /sys/class/net/br0/bridge/multicast_querier\n  echo 0xffffffffffffffff >\n  \t/sys/class/net/br0/bridge/multicast_query_interval\n  ip link set dev br0 up\n\nThe multicast_startup_query_interval can also cause this issue. Similar to\nthe commit 99b40610956a (\"net: bridge: mcast: add and enforce query\ninterval minimum\"), add check for the query interval maximum to fix this\nissue.\n\n## Affected\n\n- `Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 34171b9e53bd1dc264f5556579f2b04f04435c73`\n- `Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 43e281fde5e76a866a4d10780c35023f16c0e432`\n- `Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 96476b043efb86a94f2badd260f7f99c97bd5893`\n- `Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < bdb19cd0de739870bb3494c815138b9dc30875c4`\n- `Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < 5bf5fce8a0c2a70d063af778fdb5b27238174cdd`\n- `Linux >= d902eee43f1951b358d7347d9165c6af21cf7b1b < d1547bf460baec718b3398365f8de33d25c5f36f`\n- `Linux 2.6.34`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}