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Unscored CVE-2025-38721 EUVD-2025-26748GHSA-6237-rh4h-82p6

netfilter: ctnetlink: fix refcount leak on table dump

Published Sep 4, 2025 · Updated Nov 10, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: kernel Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.15 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.4 Package: linux-aws-5.8 Package: linux-aws-6.14 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-fips Package: linux-aws-hwe Package: linux-azure Package: linux-azure-4.15 Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.15 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.4 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.14 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-4.15 Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.15 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.4 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.14 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-fips Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.15 Package: linux-hwe-5.19 Package: linux-hwe-5.4 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.14 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-5.4 Package: linux-ibm-6.8 Package: linux-intel Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 Package: linux-iot Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-lowlatency-hwe-6.8 Package: linux-lts-xenial Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 Package: linux-nvidia-tegra-igx Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.14 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.15 Package: linux-oracle-5.3 Package: linux-oracle-5.4 Package: linux-oracle-5.8 Package: linux-oracle-6.14 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-raspi Package: linux-raspi-5.4 Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.15 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.14 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Azure Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

In the Linux kernel, the following vulnerability has been resolved:

netfilter: ctnetlink: fix refcount leak on table dump

There is a reference count leak in ctnetlink_dump_table():
if (res < 0) {
nf_conntrack_get(&ct->ct_general); // HERE
cb->args[1] = (unsigned long)ct;
...

While its very unlikely, its possible that ct == last.
If this happens, then the refcount of ct was already incremented.
This 2nd increment is never undone.

This prevents the conntrack object from being released, which in turn
keeps prevents cnet->count from dropping back to 0.

This will then block the netns dismantle (or conntrack rmmod) as
nf_conntrack_cleanup_net_list() will wait forever.

This can be reproduced by running conntrack_resize.sh selftest in a loop.
It takes ~20 minutes for me on a preemptible kernel on average before
I see a runaway kworker spinning in nf_conntrack_cleanup_net_list.

One fix would to change this to:
if (res < 0) {
if (ct != last)
nf_conntrack_get(&ct->ct_general);

But this reference counting isn't needed in the first place.
We can just store a cookie value instead.

A followup patch will do the same for ctnetlink_exp_dump_table,
it looks to me as if this has the same problem and like
ctnetlink_dump_table, we only need a 'skip hint', not the actual
object so we can apply the same cookie strategy there as well.

Affected products

VendorProductAffectedFixed
Linux Linux 2.6.18 5.4.297

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 linux 6.16.3-1 —
Debian 13 linux 6.12.43-1 —
Debian 12 linux 6.1.153-1 DSA-6009-1
Debian 11 linux 5.10.244-1 DLA-4327-1
Debian 11 linux-6.1 6.1.153-1~deb11u1 DLA-4328-1
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1016.20 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1081.83 —
Ubuntu 25.10 linux-azure-fde No fix yet —
Ubuntu 24.04 LTS linux 6.8.0-100.100 USN-8028-1
Ubuntu 24.04 LTS linux-aws +1 6.8.0-1046.49 USN-8028-5
Ubuntu 24.04 LTS linux-azure 6.8.0-1046.52 USN-8074-1
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1046.53 —
Ubuntu 24.04 LTS linux-azure-nvidia 6.8.0-1039.42 —
Ubuntu 24.04 LTS linux-gcp 6.8.0-1047.50 USN-8031-3
Ubuntu 24.04 LTS linux-gke 6.8.0-1043.48 USN-8031-3
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1030.33 USN-8028-5
Ubuntu 24.04 LTS linux-ibm 6.8.0-1044.44 USN-8028-8
Ubuntu 24.04 LTS linux-intel +19 No fix yet —
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-100.100.1 USN-8052-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1046.49.1 USN-8028-7
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1020.20 —
Ubuntu 24.04 LTS linux-oracle 6.8.0-1043.44 USN-8028-5
Ubuntu 24.04 LTS linux-raspi 6.8.0-1047.51 USN-8028-1
Ubuntu 24.04 LTS linux-xilinx 6.8.0-1023.24 USN-8052-2
Ubuntu 22.04 LTS linux +1 5.15.0-163.173 USN-7909-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1097.104 USN-7909-1
Ubuntu 22.04 LTS linux-aws-6.8 +1 6.8.0-1046.49~22.04.1 USN-8028-5
Ubuntu 22.04 LTS linux-azure 5.15.0-1101.110 USN-7910-2
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1051.57~22.04.1 USN-8126-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1102.111.1 —
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1046.53~22.04.1 —
Ubuntu 22.04 LTS linux-gcp 5.15.0-1097.106 USN-7909-4
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1047.50~22.04.2 USN-8031-1
Ubuntu 22.04 LTS linux-gke 5.15.0-1093.99 USN-7909-4
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1080.88 USN-7909-4
Ubuntu 22.04 LTS linux-hwe-6.8 +1 6.8.0-100.100~22.04.1 USN-8028-6
Ubuntu 22.04 LTS linux-ibm +1 5.15.0-1091.94 USN-7909-5, USN-7909-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1044.44~22.04.1 USN-8028-8
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1092.98 USN-7909-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1089.94 USN-7933-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-100.100.1~22.04.1 USN-8028-6
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1092.93 USN-7909-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1049.49 USN-7909-1
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1038.38 USN-7909-1
Ubuntu 22.04 LTS linux-oracle 5.15.0-1094.100 USN-7909-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1043.44~22.04.1 USN-8028-5
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1061.65 USN-7909-1
Show 18 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2037.38 USN-8028-3
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1041.42 USN-8028-3
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1089.91 USN-7909-2
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1096.105 USN-7909-2
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1041.42~22.04.1 USN-8028-2
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS 16.04 LTS linux-fips No fix yet —
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1046.49+fips1 USN-8028-4
Ubuntu Pro FIPS-updates 24.04 LTS linux-azure-fips 6.8.0-1046.52+fips1 USN-8074-2
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-100.100+fips1 USN-8028-4
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips 6.8.0-1047.50+fips1 USN-8031-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1097.104+fips1 USN-7909-3
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1101.110+fips1 USN-7910-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-163.173+fips1 USN-7909-3
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1097.106+fips1 USN-7909-3
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 16.04 LTS linux-fips No fix yet —
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux +10 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 5.15.0-1097.104~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-azure-5.15 5.15.0-1102.111~20.04.1 USN-7938-1
Ubuntu Pro 20.04 LTS linux-gcp-5.15 5.15.0-1097.106~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-hwe-5.15 +1 5.15.0-163.173~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-ibm-5.15 5.15.0-1091.94~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-intel-iotg-5.15 5.15.0-1092.98~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1049.49~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-oracle-5.15 5.15.0-1094.100~20.04.1 USN-7909-1
Ubuntu Pro 20.04 LTS linux-riscv-5.15 5.15.0-1092.96~20.04.1 —
Ubuntu Pro 18.04 LTS linux +12 No fix yet —
Ubuntu Pro 16.04 LTS linux +7 No fix yet —
Ubuntu Pro 14.04 LTS linux +3 No fix yet —
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +6 6.4.0-150700.53.19.1 SUSE-SU-2025:03601-1
SLES 15 SP7 kernel-azure +1 6.4.0-150700.20.15.2 SUSE-SU-2025:03633-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.19.1.150700.17.13.1 SUSE-SU-2025:03601-1
SLES 15 SP7 kernel-syms-azure 6.4.0-150700.20.15.1 SUSE-SU-2025:03633-1
SLES 15 SP6 kernel-64kb +6 6.4.0-150600.23.73.1 SUSE-SU-2025:03600-1
SLES 15 SP6 kernel-azure +2 6.4.0-150600.8.52.1 SUSE-SU-2025:03634-1
SLES 15 SP6 kernel-coco +3 6.4.0-15061.32.coco15sp6.1 SUSE-SU-2025:03602-1
SLES 15 SP6 kernel-default-base 6.4.0-150600.23.73.1.150600.12.32.1 SUSE-SU-2025:03600-1
Show 9 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 kernel-64kb +7 6.12.0-160000.6.1 SUSE-SU-2025:21139-1
SLES for SAP 16.0 kernel-default-base 6.12.0-160000.6.1.160000.2.4 SUSE-SU-2025:21139-1
SLES 16.0 kernel-64kb +7 6.12.0-160000.6.1 SUSE-SU-2025:21179-1, SUSE-SU-2025:21139-1
SLES 16.0 kernel-default-base 6.12.0-160000.6.1.160000.2.4 SUSE-SU-2025:21139-1
SLE Micro 6.2 kernel-default-base 6.12.0-160000.6.1.160000.2.4 SUSE-SU-2025:21074-1
SLE Micro 6.2 kernel-rt +5 6.12.0-160000.6.1 SUSE-SU-2026:20560-1, SUSE-SU-2025:21074-1
SLE Micro 6.1 kernel-default-base 6.4.0-35.1.21.12 SUSE-SU-2025:20861-1
SLE Micro 6.1 kernel-rt +1 6.4.0-37.1 SUSE-SU-2025:20898-1
SLE Micro 6.1 kernel-source +2 6.4.0-35.1 SUSE-SU-2025:20861-1
SLE Micro 6.0 kernel-default-base 6.4.0-35.1.21.12 SUSE-SU-2025:20851-1
SLE Micro 6.0 kernel-rt +1 6.4.0-37.1 SUSE-SU-2025:20870-1
SLE Micro 6.0 kernel-source +2 6.4.0-35.1 SUSE-SU-2025:20851-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.19.1 SUSE-SU-2025:03601-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_5 1-150700.1.3.1 SUSE-SU-2025:3725-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_5 1-150700.15.3.1 SUSE-SU-2025:03601-1
SLE Live Patching 15 SP6 kernel-default 6.4.0-150600.23.73.1 SUSE-SU-2025:03600-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6-RT_Update_16 1-150600.1.3.1 SUSE-SU-2025:3751-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_16 1-150600.13.3.1 SUSE-SU-2025:03600-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.19.1 SUSE-SU-2025:3725-1
SUSE Real Time Module 15 SP6 kernel-rt +3 6.4.0-150600.10.55.1 SUSE-SU-2025:3751-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 kernel-default-base 6.12.0-160000.6.1.160000.2.4 openSUSE-SU-2025:20081-1
openSUSE Leap 16.0 kernel-rt +10 6.12.0-160000.6.1 openSUSE-SU-2025:20081-1
openSUSE Leap 15.6 dtb-aarch64 +10 6.4.0-150600.23.73.1 SUSE-SU-2025:03600-1
openSUSE Leap 15.6 kernel-azure +2 6.4.0-150600.8.52.1 SUSE-SU-2025:03634-1
openSUSE Leap 15.6 kernel-default-base 6.4.0-150600.23.73.1.150600.12.32.1 SUSE-SU-2025:03600-1
openSUSE Leap 15.6 kernel-rt +3 6.4.0-150600.10.55.1 SUSE-SU-2025:3751-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.12.46-66.121 +1 1:1.0-0.amzn2023 ALAS2023-2025-1208, ALAS2023-2025-1186
Amazon Linux 2023 perf +14 1:6.1.150-174.273.amzn2023 ALAS2023-2025-1186
Amazon Linux 2023 perf6.12 +14 1:6.12.46-66.121.amzn2023 ALAS2023-2025-1208

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 kernel 6.6.104.2-1 —
Azure Linux 2 (CBL-Mariner) kernel 5.15.200.1-1 —

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-104.43.4.2.el10uek ELSA-2025-20662
Oracle Linux 8 bpftool +18 5.15.0-314.193.5.3.el9uek ELSA-2025-25757
Oracle Linux 7 kernel-uek +6 5.4.17-2136.348.3.el8uek ELSA-2025-20663
Oracle Linux 7 kernel-uek-tools 5.4.17-2136.348.3.el7uek ELSA-2025-20663

Advisories 50

References