cbcvebase.
CVE-2025-68206
published 2025-12-16

CVE-2025-68206: In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_ct: add seqadj extension for natted connections Sequence adjustment may be…

PriorityP344high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.60%
45.3th percentile
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 th

Affected

60 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.17.9-1 (forky)linux 6.17.9-1 (forky)
linuxlinux
linuxlinux>= 1a64edf54f55d7956cf5a0d95898bc1f84f9b818 < 83273af0b60c093ba0085c205864d8542e1b165383273af0b60c093ba0085c205864d8542e1b1653
linuxlinux>= 1a64edf54f55d7956cf5a0d95898bc1f84f9b818 < b19492c25eff04852e0cb58f9bb8238b6695ed2db19492c25eff04852e0cb58f9bb8238b6695ed2d
linuxlinux>= 1a64edf54f55d7956cf5a0d95898bc1f84f9b818 < 4de80f0dc3868408dd7fe9817e507123c9dd8bb04de80f0dc3868408dd7fe9817e507123c9dd8bb0
linuxlinux>= 1a64edf54f55d7956cf5a0d95898bc1f84f9b818 < b477ef7fa612fa45b6b3134d90d1eeb09396500ab477ef7fa612fa45b6b3134d90d1eeb09396500a
linuxlinux>= 1a64edf54f55d7956cf5a0d95898bc1f84f9b818 < 4ab2cd906e4e1a19ddbda6eb532851b0e9cda1104ab2cd906e4e1a19ddbda6eb532851b0e9cda110
linuxlinux>= 1a64edf54f55d7956cf5a0d95898bc1f84f9b818 < 2b52d89cbbb0dbe3e948d8d9a91e704316dccfe62b52d89cbbb0dbe3e948d8d9a91e704316dccfe6
linuxlinux>= 1a64edf54f55d7956cf5a0d95898bc1f84f9b818 < 90918e3b6404c2a37837b8f11692471b4c512de290918e3b6404c2a37837b8f11692471b4c512de2
linuxlinux_kernel>= 0 < 6.12.69-16.12.69-1
linuxlinux_kernel>= 0 < 6.17.9-16.17.9-1
linuxlinux_kernel>= 0 < 6.17.0-14.146.17.0-14.14
linuxlinux_kernel>= 4.12.0 < 6.1.1676.1.167
linuxlinux_kernel>= 6.13.0 < 6.17.96.17.9
linuxlinux_kernel>= 6.2.0 < 6.6.1306.6.130
linuxlinux_kernel>= 6.7.0 < 6.12.646.12.64
msrcazl3_kernel_6.6.117.1-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.119.3-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.119.3-3_on_azure_linux_3.0
msrcazl3_kernel_6.6.121.1-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.126.1-1_on_azure_linux_3.0
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-5.15
ubuntulinux-aws-fips

CVSS provenance

nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vendor_msrc9.1CRITICAL
vendor_ubuntu7.1HIGH
vendor_redhat5.5LOW
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