{"id":"CVE-2025-68206","revision":"be8386b3e05b4a7692325fe6f82d7650","records":[{"revision":"be8386b3e05b4a7692325fe6f82d7650","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-68206","aliases":[],"title":"netfilter: nft_ct: add seqadj extension for natted connections","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_ct: add seqadj extension for natted connections\n\nSequence adjustment may be required for FTP traffic with PASV/EPSV modes.\ndue to need to re-write packet payload (IP, port) on the ftp control\nconnection. This can require changes to the TCP length and expected\nseq / ack_seq.\n\nThe easiest way to reproduce this issue is with PASV mode.\nExample ruleset:\ntable inet ftp_nat {\n        ct helper ftp_helper {\n                type \"ftp\" protocol tcp\n                l3proto inet\n        }\n\n        chain prerouting {\n                type filter hook prerouting priority 0; policy accept;\n                tcp dport 21 ct state new ct helper set \"ftp_helper\"\n        }\n}\ntable ip nat {\n        chain prerouting {\n                type nat hook prerouting priority -100; policy accept;\n                tcp dport 21 dnat ip prefix to ip daddr map {\n\t\t\t192.168.100.1 : 192.168.13.2/32 }\n        }\n\n        chain postrouting {\n                type nat hook postrouting priority 100 ; policy accept;\n                tcp sport 21 snat ip prefix to ip saddr map {\n\t\t\t192.168.13.2 : 192.168.100.1/32 }\n        }\n}\n\nNote that the ftp helper gets assigned *after* the dnat setup.\n\nThe inverse (nat after helper assign) is handled by an existing\ncheck in nf_nat_setup_info() and will not show the problem.\n\nTopoloy:\n\n +-------------------+     +----------------------------------+\n | FTP: 192.168.13.2 | <-> | NAT: 192.168.13.3, 192.168.100.1 |\n +-------------------+     +----------------------------------+\n                                      |\n                         +-----------------------+\n                         | Client: 192.168.100.2 |\n                         +-----------------------+\n\nftp nat changes do not work as expected in this case:\nConnected to 192.168.100.1.\n[..]\nftp> epsv\nEPSV/EPRT on IPv4 off.\nftp> ls\n227 Entering passive mode (192,168,100,1,209,129).\n421 Service not available, remote server has closed connection.\n\nKernel logs:\nMissing nfct_seqadj_ext_add() setup call\nWARNING: CPU: 1 PID: 0 at net/netfilter/nf_conntrack_seqadj.c:41\n[..]\n __nf_nat_mangle_tcp_packet+0x100/0x160 [nf_nat]\n nf_nat_ftp+0x142/0x280 [nf_nat_ftp]\n help+0x4d1/0x880 [nf_conntrack_ftp]\n nf_confirm+0x122/0x2e0 [nf_conntrack]\n nf_hook_slow+0x3c/0xb0\n ..\n\nFix this by adding the required extension when a conntrack helper is assigned\nto a connection that has a nat binding.","state":0,"publishedAt":"2025-12-16T13:48:33.763+00:00","modifiedAt":"2026-10-15T22:02:47.582+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/netfilter/nft_ct.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"1a64edf54f55d7956cf5a0d95898bc1f84f9b818\",\n                            \"lessThan\": \"83273af0b60c093ba0085c205864d8542e1b1653\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a64edf54f55d7956cf5a0d95898bc1f84f9b818\",\n                            \"lessThan\": \"b19492c25eff04852e0cb58f9bb8238b6695ed2d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a64edf54f55d7956cf5a0d95898bc1f84f9b818\",\n                            \"lessThan\": \"4de80f0dc3868408dd7fe9817e507123c9dd8bb0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a64edf54f55d7956cf5a0d95898bc1f84f9b818\",\n                            \"lessThan\": \"b477ef7fa612fa45b6b3134d90d1eeb09396500a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a64edf54f55d7956cf5a0d95898bc1f84f9b818\",\n                            \"lessThan\": \"4ab2cd906e4e1a19ddbda6eb532851b0e9cda110\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a64edf54f55d7956cf5a0d95898bc1f84f9b818\",\n                            \"lessThan\": \"2b52d89cbbb0dbe3e948d8d9a91e704316dccfe6\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a64edf54f55d7956cf5a0d95898bc1f84f9b818\",\n                            \"lessThan\": \"90918e3b6404c2a37837b8f11692471b4c512de2\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/netfilter/nft_ct.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.12\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.12\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.253\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.203\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.167\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.130\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.64\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.17.9\",\n                            \"lessThanOrEqual\": \"6.17.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/83273af0b60c093ba0085c205864d8542e1b1653","https://git.kernel.org/stable/c/b19492c25eff04852e0cb58f9bb8238b6695ed2d","https://git.kernel.org/stable/c/4de80f0dc3868408dd7fe9817e507123c9dd8bb0","https://git.kernel.org/stable/c/b477ef7fa612fa45b6b3134d90d1eeb09396500a","https://git.kernel.org/stable/c/4ab2cd906e4e1a19ddbda6eb532851b0e9cda110","https://git.kernel.org/stable/c/2b52d89cbbb0dbe3e948d8d9a91e704316dccfe6","https://git.kernel.org/stable/c/90918e3b6404c2a37837b8f11692471b4c512de2"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-68206","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-68206","identifiers":["CVE-2025-68206"]},"retained":false,"historicalAffected":[]}],"coverage":[]}