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Vulnerabilities

Vulnerability · CVE-2025-39773

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,

Published Sep 11, 2025 · catalog updated Oct 19, 2026 · Linux Linux

Check if you run it

No confirmed exploitation is on record for CVE-2025-39773. EPSS is 0.12%. Act only if a listed version of Linux Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.12%
Remediation
Advisory link
Affected products
cpe debian/debian linux · cpe linux/linux kernel · vendor Linux Linux patch: 6.1.149

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: __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 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe debian/debian linux11.0
  • cpe linux/linux kernel6.17
  • vendor Linux Linux patch: 6.1.149patch: 6.1.149

How to fix CVE-2025-39773

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-39773. EPSS is 0.12%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with debian/debian linux 11.0; linux/linux kernel 6.17; Linux Linux patch: 6.1.149 patch: 6.1.149. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-667. EPSS 0.12%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 11, 2025 · NIST NVD

    Detected

    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 foll

  2. Oct 15, 2026 · NIST NVD

    Updated

    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 foll

  3. Oct 19, 2026 · NIST NVD

    Updated

    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 foll

Sources

  • CVE.orgVulnerability recordCVE-2025-39773

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-39773

    30-day exploitation probability 0.1%

    first.org
  • EUVDVulnerability recordEUVD-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 ji

    euvd.enisa.europa.eu
  • NIST NVDVulnerability recordCVE-2025-39773

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.