CVE-2025-39773

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-09-11. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
1.6%
KEV
Not listed

Published

September 11, 2025

Last Modified

July 14, 2026

Advisory Details (10)

Auto-updated Jul 19, 2026
⚠️ Active exploitation confirmed. Patch available.
generic🔴 Active Exploitation

SSA-082556

https://cert-portal.siemens.com/productcert/html/ssa-082556.html
generic

SSA-032379

https://cert-portal.siemens.com/productcert/html/ssa-032379.html
generic

SSA-019113

https://cert-portal.siemens.com/productcert/html/ssa-019113.html
generic Patch Available

[SECURITY] [DLA 4328-1] linux-6.1 security update

https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
generic

net: bridge: fix soft lockup in br_multicast_query_expired() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d1547bf460baec718b3398365f8de33d25c5f36f
generic

net: bridge: fix soft lockup in br_multicast_query_expired() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bdb19cd0de739870bb3494c815138b9dc30875c4
generic

net: bridge: fix soft lockup in br_multicast_query_expired() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/96476b043efb86a94f2badd260f7f99c97bd5893
generic

net: bridge: fix soft lockup in br_multicast_query_expired() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5bf5fce8a0c2a70d063af778fdb5b27238174cdd
generic

net: bridge: fix soft lockup in br_multicast_query_expired() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/43e281fde5e76a866a4d10780c35023f16c0e432
generic

net: bridge: fix soft lockup in br_multicast_query_expired() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/34171b9e53bd1dc264f5556579f2b04f04435c73

Vendor Advisories for CVE-2025-39773(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(26)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-gcp-edge (6.8.0-1047.50~22.04.2) @ jammy2026-05-21ubuntu
ubuntulinux-tools-azure-fips-5.15 (5.15.0.1101.86) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gkeop-5.15 (5.15.0.1080.79) @ jammy2026-05-21ubuntu
ubuntulinux-tools-realtime-5.15 (5.15.0.1096.100) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gcp-fips-5.15 (5.15.0.1097.87) @ jammy2026-05-21ubuntu
ubuntulinux-tools-azure-lts-22.04 (5.15.0.1101.99) @ jammy2026-05-21ubuntu
ubuntulinux-tools-raspi-nolpae (5.15.0.1091.89) @ jammy2026-05-21ubuntu
ubuntulinux-tools-realtime-hwe-22.04 (6.8.1-1041.42~22.04.1) @ jammy2026-05-21ubuntu
ubuntulinux-tools-kvm-5.15 (5.15.0.1089.85) @ jammy2026-05-21ubuntu
ubuntulinux-tools-azure-edge (5.15.0.1102.111~20.04.1) @ focal2026-05-21ubuntu
ubuntulinux-virtual-6.8 (6.8.0-100.100) @ noble2026-05-21ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1023.24) @ noble2026-05-21ubuntu
ubuntulinux-tools-lowlatency-hwe-20.04-edge (6.8.0-100.100.1) @ noble2026-05-21ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1046.49.1) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1046.52+fips1) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1046.52) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1051.57~22.04.1) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gke-64k-6.8 (6.8.0-1043.48) @ noble2026-05-21ubuntu
ubuntulinux-tools-ibm-edge (6.8.0-1044.44~22.04.1) @ jammy2026-05-21ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.15.0-1061 (5.15.0-1061.65) @ jammy2026-05-21ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-100.100~22.04.1) @ jammy2026-05-21ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1047.50+fips1) @ noble2026-05-21ubuntu
ubuntulinux-tools-fips-6.8 (6.8.0-100.100+fips1) @ noble2026-05-21ubuntu
ubuntulinux-tools-realtime-6.8.1 (6.8.1-1041.42) @ noble2026-05-21ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1043.44) @ noble2026-05-21ubuntu
linuxKernel @ 5.15.190—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(24)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 38× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 114 total refreshes for this CVE.

  1. 2026-07-24 14:17 UTCEPSS rescore
  2. 2026-07-23 02:55 UTCEG score recompute
  3. 2026-07-22 14:07 UTCEPSS rescore
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  15. 2026-07-14 13:19 UTCNVD updateCVSS v3 → 5.5 · severity → MEDIUM
  16. 2026-07-14 13:11 UTCMITRE cvelistV5
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Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2025-39773?
CVE-2025-39773 is a medium vulnerability published on September 11, 2025. In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix soft lockup in brmulticastquery_expired() When set multicastqueryinterval to a large value, the local variable 'time' in brmulticastsend_query() may overflow. If the time is smaller than jiffies, the timer will…
When was CVE-2025-39773 disclosed?
CVE-2025-39773 was first published in the National Vulnerability Database on September 11, 2025, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-39773 actively exploited?
CVE-2025-39773 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-39773?
CVE-2025-39773 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-39773?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-39773, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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