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CVE-2025-39773· NVD / CVE Program· CNA Linux

net: bridge: fix soft lockup in br_multicast_query_expired()

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 34171b9e53bd1dc264f5556579f2b04f04435c73, 43e281fde5e76a866a4d10780c35023f16c0e432, 5bf5fce8a0c2a70d063af778fdb5b27238174cdd; azl3 kernel 6.6.96.2-2 on Azure Linux 3.0 6.6.104.2-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1.

Low priority for now. Upgrade to Linux Linux 34171b9e53bd1dc264f5556579f2b04f04435c73, 43e281fde5e76a866a4d10780c35023f16c0e432, 5bf5fce8a0c2a70d063af778fdb5b27238174cdd; azl3 kernel 6.6.96.2-2 on Azure Linux 3.0 6.6.104.2-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Sep 11, 2025
Updated
Sep 8, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux11.0
  • linux linux kernel5.16 and later · before 6.1.149
  • linux linux kernel6.2 and later · before 6.6.103
  • linux linux kernel2.6.34 and later · before 5.15.190
  • linux linux kernel6.13 and later · before 6.16.4
  • linux linux kernel6.7 and later · before 6.12.44
  • linux linux kernel6.17

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.34affected
    • d902eee43f1951b358d7347d9165c6af21cf7b1b and later · before 34171b9e53bd1dc264f5556579f2b04f04435c73affected · git
    • d902eee43f1951b358d7347d9165c6af21cf7b1b and later · before 43e281fde5e76a866a4d10780c35023f16c0e432affected · git
    • d902eee43f1951b358d7347d9165c6af21cf7b1b and later · before 96476b043efb86a94f2badd260f7f99c97bd5893affected · git
    • d902eee43f1951b358d7347d9165c6af21cf7b1b and later · before bdb19cd0de739870bb3494c815138b9dc30875c4affected · git
    • d902eee43f1951b358d7347d9165c6af21cf7b1b and later · before 5bf5fce8a0c2a70d063af778fdb5b27238174cddaffected · git
    • d902eee43f1951b358d7347d9165c6af21cf7b1b and later · before d1547bf460baec718b3398365f8de33d25c5f36faffected · git
    • before 2.6.34not affected · semver
    • 5.15.190 and later · up to and including 5.15.*not affected · semver
    • 6.1.149 and later · up to and including 6.1.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.153-16.1.153-1
Debian:13linuxbefore 6.12.48-16.12.48-1
Debian:14linuxbefore 6.16.5-16.16.5-1

Same product

linux: all records

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  • CVE-2016-5195Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect haKEV
    83Now
  • CVE-2019-13272In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to creKEV
    77This week
  • CVE-2013-6282The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the v6k and v7 ARM platforms do not validate certain addKEV
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    77This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux34171b9e53bd1dc264f5556579f2b04f04435c73Vendor (CNA)
Linux Linux43e281fde5e76a866a4d10780c35023f16c0e432Vendor (CNA)
Linux Linux5bf5fce8a0c2a70d063af778fdb5b27238174cddVendor (CNA)
Linux Linux96476b043efb86a94f2badd260f7f99c97bd5893Vendor (CNA)
Linux Linuxbdb19cd0de739870bb3494c815138b9dc30875c4Vendor (CNA)
Linux Linuxd1547bf460baec718b3398365f8de33d25c5f36fVendor (CNA)
azl3 kernel 6.6.96.2-2 on Azure Linux 3.06.6.104.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.05.15.200.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.153-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-667 · Improper Locking

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (9 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records