{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-68227","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-12-16T13:41:40.257Z","datePublished":"2025-12-16T13:57:20.027Z","dateUpdated":"2026-05-11T21:49:17.263Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-05-11T21:49:17.263Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: Fix proto fallback detection with BPF\n\nThe sockmap feature allows bpf syscall from userspace, or based\non bpf sockops, replacing the sk_prot of sockets during protocol stack\nprocessing with sockmap's custom read/write interfaces.\n'''\ntcp_rcv_state_process()\n  syn_recv_sock()/subflow_syn_recv_sock()\n    tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB)\n      bpf_skops_established       <== sockops\n        bpf_sock_map_update(sk)   <== call bpf helper\n          tcp_bpf_update_proto()  <== update sk_prot\n'''\n\nWhen the server has MPTCP enabled but the client sends a TCP SYN\nwithout MPTCP, subflow_syn_recv_sock() performs a fallback on the\nsubflow, replacing the subflow sk's sk_prot with the native sk_prot.\n'''\nsubflow_syn_recv_sock()\n  subflow_ulp_fallback()\n    subflow_drop_ctx()\n      mptcp_subflow_ops_undo_override()\n'''\n\nThen, this subflow can be normally used by sockmap, which replaces the\nnative sk_prot with sockmap's custom sk_prot. The issue occurs when the\nuser executes accept::mptcp_stream_accept::mptcp_fallback_tcp_ops().\nHere, it uses sk->sk_prot to compare with the native sk_prot, but this\nis incorrect when sockmap is used, as we may incorrectly set\nsk->sk_socket->ops.\n\nThis fix uses the more generic sk_family for the comparison instead.\n\nAdditionally, this also prevents a WARNING from occurring:\n\nresult from ./scripts/decode_stacktrace.sh:\n------------[ cut here ]------------\nWARNING: CPU: 0 PID: 337 at net/mptcp/protocol.c:68 mptcp_stream_accept \\\n(net/mptcp/protocol.c:4005)\nModules linked in:\n...\n\nPKRU: 55555554\nCall Trace:\n<TASK>\ndo_accept (net/socket.c:1989)\n__sys_accept4 (net/socket.c:2028 net/socket.c:2057)\n__x64_sys_accept (net/socket.c:2067)\nx64_sys_call (arch/x86/entry/syscall_64.c:41)\ndo_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\nentry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\nRIP: 0033:0x7f87ac92b83d\n\n---[ end trace 0000000000000000 ]---"}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/protocol.c"],"versions":[{"version":"0b4f33def7bbde1ce2fea05f116639270e7acdc7","lessThan":"92c4092fe012ecdfa5fb05d394f1c1d8f91ad81c","status":"affected","versionType":"git"},{"version":"0b4f33def7bbde1ce2fea05f116639270e7acdc7","lessThan":"7ee8f015eb47907745e2070184a8ab1e442ac3c4","status":"affected","versionType":"git"},{"version":"0b4f33def7bbde1ce2fea05f116639270e7acdc7","lessThan":"344974ea1a3ca30e4920687b0091bda4438cebdb","status":"affected","versionType":"git"},{"version":"0b4f33def7bbde1ce2fea05f116639270e7acdc7","lessThan":"037cc50589643342d69185b663ecf9d26cce91e8","status":"affected","versionType":"git"},{"version":"0b4f33def7bbde1ce2fea05f116639270e7acdc7","lessThan":"9b1980b6f23fa30bf12add19f37c7458625099eb","status":"affected","versionType":"git"},{"version":"0b4f33def7bbde1ce2fea05f116639270e7acdc7","lessThan":"1a0d5c74af9b6ba9ffdf1172de5a1a6df5922a00","status":"affected","versionType":"git"},{"version":"0b4f33def7bbde1ce2fea05f116639270e7acdc7","lessThan":"c77b3b79a92e3345aa1ee296180d1af4e7031f8f","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/protocol.c"],"versions":[{"version":"5.7","status":"affected"},{"version":"0","lessThan":"5.7","status":"unaffected","versionType":"semver"},{"version":"5.10.247","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.197","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.159","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.118","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.60","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.17.10","lessThanOrEqual":"6.17.*","status":"unaffected","versionType":"semver"},{"version":"6.18","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.10.247"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.15.197"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.1.159"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.6.118"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.12.60"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.17.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.18"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/92c4092fe012ecdfa5fb05d394f1c1d8f91ad81c"},{"url":"https://git.kernel.org/stable/c/7ee8f015eb47907745e2070184a8ab1e442ac3c4"},{"url":"https://git.kernel.org/stable/c/344974ea1a3ca30e4920687b0091bda4438cebdb"},{"url":"https://git.kernel.org/stable/c/037cc50589643342d69185b663ecf9d26cce91e8"},{"url":"https://git.kernel.org/stable/c/9b1980b6f23fa30bf12add19f37c7458625099eb"},{"url":"https://git.kernel.org/stable/c/1a0d5c74af9b6ba9ffdf1172de5a1a6df5922a00"},{"url":"https://git.kernel.org/stable/c/c77b3b79a92e3345aa1ee296180d1af4e7031f8f"}],"title":"mptcp: Fix proto fallback detection with BPF","x_generator":{"engine":"bippy-1.2.0"}}}}