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High · 7.5 CVE-2025-68206 EUVD-2025-203690GHSA-9r97-6c49-v2hf

netfilter: nft_ct: add seqadj extension for natted connections

Published Dec 16, 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-6.17 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-5.15 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-6.17 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-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-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 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-6.17 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-6.17 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-6.17 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: nft_ct: add seqadj extension for natted connections

Sequence adjustment may be required for FTP traffic with PASV/EPSV modes.
due to need to re-write packet payload (IP, port) on the ftp control
connection. This can require changes to the TCP length and expected
seq / ack_seq.

The easiest way to reproduce this issue is with PASV mode.
Example ruleset:
table inet ftp_nat {
ct helper ftp_helper {
type "ftp" protocol tcp
l3proto inet
}

chain prerouting {
type filter hook prerouting priority 0; policy accept;
tcp dport 21 ct state new ct helper set "ftp_helper"
}
}
table ip nat {
chain prerouting {
type nat hook prerouting priority -100; policy accept;
tcp dport 21 dnat ip prefix to ip daddr map {
192.168.100.1 : 192.168.13.2/32 }
}

chain postrouting {
type nat hook postrouting priority 100 ; policy accept;
tcp sport 21 snat ip prefix to ip saddr map {
192.168.13.2 : 192.168.100.1/32 }
}
}

Note that the ftp helper gets assigned *after* the dnat setup.

The inverse (nat after helper assign) is handled by an existing
check in nf_nat_setup_info() and will not show the problem.

Topoloy:

+-------------------+ +----------------------------------+
| FTP: 192.168.13.2 | <-> | NAT: 192.168.13.3, 192.168.100.1 |
+-------------------+ +----------------------------------+
|
+-----------------------+
| Client: 192.168.100.2 |
+-----------------------+

ftp nat changes do not work as expected in this case:
Connected to 192.168.100.1.
[..]
ftp> epsv
EPSV/EPRT on IPv4 off.
ftp> ls
227 Entering passive mode (192,168,100,1,209,129).
421 Service not available, remote server has closed connection.

Kernel logs:
Missing nfct_seqadj_ext_add() setup call
WARNING: CPU: 1 PID: 0 at net/netfilter/nf_conntrack_seqadj.c:41
[..]
__nf_nat_mangle_tcp_packet+0x100/0x160 [nf_nat]
nf_nat_ftp+0x142/0x280 [nf_nat_ftp]
help+0x4d1/0x880 [nf_conntrack_ftp]
nf_confirm+0x122/0x2e0 [nf_conntrack]
nf_hook_slow+0x3c/0xb0
..

Fix this by adding the required extension when a conntrack helper is assigned
to a connection that has a nat binding.

Affected products

VendorProductAffectedFixed
Linux Linux 4.12 5.10.253

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 6.17.9-1 —
Debian 13 linux 6.12.69-1 DSA-6126-1
Debian 12 linux 6.1.170-1 —
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1017.21 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1096.98 —
Ubuntu 25.10 linux 6.17.0-14.14 USN-8029-1
Ubuntu 25.10 linux-aws +2 6.17.0-1007.7 USN-8030-1, USN-8029-2
Ubuntu 25.10 linux-azure +1 6.17.0-1008.8 USN-8029-3, USN-8029-1
Ubuntu 25.10 linux-azure-fde No fix yet —
Ubuntu 25.10 linux-realtime 6.17.0-1006.7 USN-8029-1
Ubuntu 25.10 linux-riscv 6.17.0-14.14.1 —
Ubuntu 24.04 LTS linux 6.8.0-110.110 USN-8179-1
Ubuntu 24.04 LTS linux-aws 6.8.0-1052.55 USN-8179-1
Ubuntu 24.04 LTS linux-aws-6.17 +1 6.17.0-1007.7~24.04.1 —
Ubuntu 24.04 LTS linux-azure 6.8.0-1054.60 USN-8258-1
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1058.65 —
Ubuntu 24.04 LTS linux-azure-nvidia 6.8.0-1039.42 —
Ubuntu 24.04 LTS linux-gcp 6.8.0-1054.57 USN-8179-1
Ubuntu 24.04 LTS linux-gcp-6.17 6.17.0-1008.8~24.04.1 —
Ubuntu 24.04 LTS linux-gke 6.8.0-1050.56 USN-8179-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1037.40 USN-8179-1
Ubuntu 24.04 LTS linux-ibm 6.8.0-1051.51 USN-8179-1
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-110.110.1 USN-8179-1
Ubuntu 24.04 LTS linux-nvidia 6.8.0-1051.54 USN-8185-1
Ubuntu 24.04 LTS linux-nvidia-6.17 6.17.0-1008.8 —
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1051.54.1 USN-8185-2
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1022.22 USN-8265-1
Ubuntu 24.04 LTS linux-oem-6.17 6.17.0-1011.11 USN-8048-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1049.50 USN-8203-1
Ubuntu 24.04 LTS linux-raspi 6.8.0-1052.56 USN-8179-3
Ubuntu 24.04 LTS linux-riscv +18 No fix yet —
Ubuntu 24.04 LTS linux-xilinx 6.8.0-1028.29 USN-8261-1
Ubuntu 22.04 LTS linux 5.15.0-186.196 USN-8575-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1112.119 USN-8575-2
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1052.55~22.04.1 USN-8179-1
Ubuntu 22.04 LTS linux-azure +1 5.15.0-1117.126 USN-8610-1, USN-8575-3
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1059.65~22.04.1 USN-8440-1
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1058.65~22.04.1 —
Ubuntu 22.04 LTS linux-gcp 5.15.0-1112.122 USN-8575-1
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1054.57~22.04.1 USN-8179-4
Ubuntu 22.04 LTS linux-gke 5.15.0-1108.114 USN-8575-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1095.103 USN-8575-1
Ubuntu 22.04 LTS linux-hwe-6.8 +1 6.8.0-110.110~22.04.1 USN-8179-3
Ubuntu 22.04 LTS linux-ibm 5.15.0-1106.110 USN-8575-2
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1051.51~22.04.1 USN-8179-3
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1107.113 USN-8620-4
Ubuntu 22.04 LTS linux-kvm 5.15.0-1104.109 USN-8575-1
Ubuntu 22.04 LTS linux-lowlatency 5.15.0-184.194 USN-8575-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-110.110.1~22.04.1 USN-8179-1
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1107.108 USN-8575-2
Ubuntu 22.04 LTS linux-nvidia-6.8 6.8.0-1051.54~22.04.1 USN-8185-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1064.66 USN-8576-2
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1053.53 USN-8576-2
Ubuntu 22.04 LTS linux-oracle 5.15.0-1109.115 USN-8575-3
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1049.50~22.04.1 USN-8203-1
Ubuntu 22.04 LTS linux-raspi 5.15.0-1106.109 USN-8668-2
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1075.79 USN-8575-1
Show 16 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 6.8.0-2042.43 USN-8204-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1047.48 USN-8184-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.17 6.17.0-1006.7~24.04.1 —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1104.106 USN-8620-3
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1111.120 USN-8575-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1047.48~22.04.1 USN-8184-1
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-updates 24.04 LTS linux-aws-fips 6.8.0-1052.55+fips1 USN-8179-2
Ubuntu Pro FIPS-updates 24.04 LTS linux-azure-fips 6.8.0-1053.59+fips1 —
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-110.110+fips2 USN-8179-2
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips 6.8.0-1054.57+fips1 USN-8179-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1112.119+fips1 USN-8575-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1117.126+fips1 USN-8620-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-186.196+fips1 USN-8575-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1112.122+fips1 USN-8575-1
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-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 5.15.0-1112.119~20.04.1 USN-8575-2
Ubuntu Pro 20.04 LTS linux-azure-5.15 5.15.0-1117.126~20.04.1 USN-8620-1
Ubuntu Pro 20.04 LTS linux-azure-fde-5.15 5.15.0-1117.126~20.04.2 USN-8620-1
Ubuntu Pro 20.04 LTS linux-gcp-5.15 5.15.0-1112.122~20.04.1 USN-8668-1
Ubuntu Pro 20.04 LTS linux-hwe-5.15 5.15.0-186.196~20.04.1 USN-8575-1
Ubuntu Pro 20.04 LTS linux-ibm-5.15 +1 5.15.0-1106.110~20.04.1 USN-8597-1
Ubuntu Pro 20.04 LTS linux-intel-iotg-5.15 5.15.0-1107.113~20.04.1 USN-8620-3
Ubuntu Pro 20.04 LTS linux-lowlatency-hwe-5.15 5.15.0-184.194~20.04.1 USN-8575-1
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1064.66~20.04.1 USN-8576-1
Ubuntu Pro 20.04 LTS linux-oracle-5.15 5.15.0-1109.115~20.04.1 USN-8620-1
Ubuntu Pro 18.04 LTS linux +12 No fix yet —
Ubuntu Pro 16.04 LTS linux-gcp +4 No fix yet —
Ubuntu Pro 14.04 LTS linux-azure No fix yet —
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +6 6.4.0-150700.53.28.1 SUSE-SU-2026:0315-1
SLES 15 SP7 kernel-azure +2 6.4.0-150700.20.24.1 SUSE-SU-2026:0281-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.28.1.150700.17.19.1 SUSE-SU-2026:0315-1
SLES 12 SP5 kernel-syms +2 4.12.14-122.290.1 SUSE-SU-2026:0316-1
Show 8 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 kernel-64kb +8 6.12.0-160000.9.1 SUSE-SU-2026:20220-1
SLES for SAP 16.0 kernel-default-base 6.12.0-160000.9.1.160000.2.6 SUSE-SU-2026:20220-1
SLES 16.0 kernel-64kb +8 6.12.0-160000.9.1 SUSE-SU-2026:20228-1, SUSE-SU-2026:20220-1
SLES 16.0 kernel-default-base 6.12.0-160000.9.1.160000.2.6 SUSE-SU-2026:20220-1
SLE Micro 6.2 kernel-default-base 6.12.0-160000.9.1.160000.2.6 SUSE-SU-2026:20207-1
SLE Micro 6.2 kernel-rt +5 6.12.0-160000.9.1 SUSE-SU-2026:20564-1, SUSE-SU-2026:20207-1
SLE Micro 6.1 kernel-default-base 6.4.0-39.1.21.16 SUSE-SU-2026:20498-1
SLE Micro 6.1 kernel-rt +1 6.4.0-40.1 SUSE-SU-2026:20876-1
SLE Micro 6.1 kernel-source +2 6.4.0-39.1 SUSE-SU-2026:20498-1
SLE Micro 6.0 kernel-default-base 6.4.0-39.1.21.16 SUSE-SU-2026:20477-1
SLE Micro 6.0 kernel-rt +1 6.4.0-40.1 SUSE-SU-2026:20845-1
SLE Micro 6.0 kernel-source +2 6.4.0-39.1 SUSE-SU-2026:20477-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.28.1 SUSE-SU-2026:0315-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_8 1-150700.1.3.1 SUSE-SU-2026:0278-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_8 1-150700.15.3.1 SUSE-SU-2026:0315-1
SLE Live Patching 12 SP5 kernel-default 4.12.14-122.290.1 SUSE-SU-2026:0316-1
SLE Live Patching 12 SP5 kgraft-patch-SLE12-SP5_Update_76 1-8.7.1 SUSE-SU-2026:0316-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.28.1 SUSE-SU-2026:0278-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 kernel-default-base 6.12.0-160000.9.1.160000.2.6 openSUSE-SU-2026:20145-1
openSUSE Leap 16.0 kernel-rt +11 6.12.0-160000.9.1 openSUSE-SU-2026:20145-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.12.64-87.122 +1 1:1.0-0.amzn2023 ALAS2023-2026-1681, ALAS2023-2026-1423
Amazon Linux 2023 perf +14 1:6.1.168-202.320.amzn2023 ALAS2023-2026-1681
Amazon Linux 2023 perf6.12 +14 1:6.12.64-87.122.amzn2023 ALAS2023-2026-1423

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 kernel 6.6.130.1-1 —

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-108.64.6.3.el10uek ELSA-2026-50112

Advisories 50

References