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VulnerabilityPublished Updated

CVE-2025-39773: Linux kernel · net: bridge: fix soft lockup in br_multicast_query_expired()

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in d1547bf460baec718b3398365f8de33d25c5f36f : update Linux kernel when convenient.

Data as of 10 Nov 2026, 12:50 UTC

Severity
Medium

Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none
Patch
Available – fixed in d1547bf460baec718b3398365f8de33d25c5f36f, bdb19cd0de739870bb3494c815138b9dc30875c4, 96476b043efb86a94f2badd260f7f99c97bd5893 +3

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Sep 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ d902eee43f1951b358d7347d9165c6af21cf7b1b, < d1547bf460baec718b3398365f8de33d25c5f36f
Fixed in
  • d1547bf460baec718b3398365f8de33d25c5f36f
LinuxLinuxAffected
  • ≥ d902eee43f1951b358d7347d9165c6af21cf7b1b, < bdb19cd0de739870bb3494c815138b9dc30875c4
Fixed in
  • bdb19cd0de739870bb3494c815138b9dc30875c4
LinuxLinuxAffected
  • ≥ d902eee43f1951b358d7347d9165c6af21cf7b1b, < 96476b043efb86a94f2badd260f7f99c97bd5893
Fixed in
  • 96476b043efb86a94f2badd260f7f99c97bd5893
LinuxLinuxAffected
  • ≥ d902eee43f1951b358d7347d9165c6af21cf7b1b, < 34171b9e53bd1dc264f5556579f2b04f04435c73
Fixed in
  • 34171b9e53bd1dc264f5556579f2b04f04435c73
LinuxLinuxAffected
  • ≥ d902eee43f1951b358d7347d9165c6af21cf7b1b, < 43e281fde5e76a866a4d10780c35023f16c0e432
Fixed in
  • 43e281fde5e76a866a4d10780c35023f16c0e432
LinuxLinuxAffected
  • ≥ d902eee43f1951b358d7347d9165c6af21cf7b1b, < 5bf5fce8a0c2a70d063af778fdb5b27238174cdd
Fixed in
  • 5bf5fce8a0c2a70d063af778fdb5b27238174cdd

AI-suggested

This issue has been fixed in the Linux kernel. Users should update to a fixed kernel version that includes the patches identified by the commit hashes provided. No additional mitigation is required once the system is updated.

Description

A vulnerability in the Linux kernel bridge networking code can cause a soft lockup due to an integer overflow in the multicast query timer logic. Setting the multicast_query_interval to a large value causes a local time variable to overflow, triggering a timer loop and CPU soft lockup. This issue has been fixed by adding checks to enforce maximum query interval values.

References

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