{"api_version":"1","generated_at":"2026-07-23T14:10:45+00:00","cve":"CVE-2026-64024","urls":{"html":"https://cve.report/CVE-2026-64024","api":"https://cve.report/api/cve/CVE-2026-64024.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64024","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64024"},"summary":{"title":"tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction\n\nBlamed commit moved the TIME_WAIT-derived ISN from the skb control\nblock to a per-CPU variable, assuming the value would always be consumed\nby tcp_conn_request() for the same packet that wrote it. That assumption\nis violated by multiple drop paths between the producer\n(__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer\n(tcp_conn_request()):\n\n - min_ttl / min_hopcount check\n - xfrm policy check\n - tcp_inbound_hash() MD5/AO mismatch\n - tcp_filter() eBPF/SO_ATTACH_FILTER drop\n - th->syn && th->fin discard in tcp_rcv_state_process() TCP_LISTEN\n - psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv()\n - tcp_checksum_complete() in tcp_v{4,6}_do_rcv()\n - tcp_v{4,6}_cookie_check() returning NULL\n\nWhen a packet is dropped on any of these paths, tcp_tw_isn is left set.\n\nThe next SYN processed on the same CPU then consumes the non zero value in\ntcp_conn_request(), receiving a potentially predictable ISN.\n\nThis patch moves back tcp_tw_isn to skb->cb[], getting rid of the per-cpu\nvariable.\n\nNote that tcp_v{4,6}_fill_cb() do not set it.\n\nVery litle impact on overall code size/complexity:\n\n$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new\nadd/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7)\nFunction                                     old     new   delta\ntcp_v6_rcv                                  3038    3042      +4\ntcp_v4_rcv                                  3035    3039      +4\ntcp_conn_request                            2938    2923     -15\nTotal: Before=24436060, After=24436053, chg -0.00%","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:17:42","updated_at":"2026-07-20 15:17:03"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.4","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H","baseScore":9.4,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.4","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H","data":{"baseScore":9.4,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/4affe063fa56c880cbea8d0bfded0bb80751579d","name":"https://git.kernel.org/stable/c/4affe063fa56c880cbea8d0bfded0bb80751579d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1bbf0ced1d9db73ac7893c2187f3459288603e0d","name":"https://git.kernel.org/stable/c/1bbf0ced1d9db73ac7893c2187f3459288603e0d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e47f7060eaf60894e3e4d0e3c4fe6e1f2eacfbdd","name":"https://git.kernel.org/stable/c/e47f7060eaf60894e3e4d0e3c4fe6e1f2eacfbdd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64024","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64024","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 41eecbd712b73f0d5dcf1152b9a1c27b1f238028 e47f7060eaf60894e3e4d0e3c4fe6e1f2eacfbdd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 41eecbd712b73f0d5dcf1152b9a1c27b1f238028 4affe063fa56c880cbea8d0bfded0bb80751579d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 41eecbd712b73f0d5dcf1152b9a1c27b1f238028 1bbf0ced1d9db73ac7893c2187f3459288603e0d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.10","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.34 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.11 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"64024","cve":"CVE-2026-64024","epss":"0.001660000","percentile":"0.061630000","score_date":"2026-07-20","updated_at":"2026-07-21 00:13:13"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/net/tcp.h","net/ipv4/tcp.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv6/tcp_ipv6.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"e47f7060eaf60894e3e4d0e3c4fe6e1f2eacfbdd","status":"affected","version":"41eecbd712b73f0d5dcf1152b9a1c27b1f238028","versionType":"git"},{"lessThan":"4affe063fa56c880cbea8d0bfded0bb80751579d","status":"affected","version":"41eecbd712b73f0d5dcf1152b9a1c27b1f238028","versionType":"git"},{"lessThan":"1bbf0ced1d9db73ac7893c2187f3459288603e0d","status":"affected","version":"41eecbd712b73f0d5dcf1152b9a1c27b1f238028","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/net/tcp.h","net/ipv4/tcp.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv6/tcp_ipv6.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.10"},{"lessThan":"6.10","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.34","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.34","versionStartIncluding":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.11","versionStartIncluding":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1","versionStartIncluding":"6.10","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction\n\nBlamed commit moved the TIME_WAIT-derived ISN from the skb control\nblock to a per-CPU variable, assuming the value would always be consumed\nby tcp_conn_request() for the same packet that wrote it. That assumption\nis violated by multiple drop paths between the producer\n(__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer\n(tcp_conn_request()):\n\n - min_ttl / min_hopcount check\n - xfrm policy check\n - tcp_inbound_hash() MD5/AO mismatch\n - tcp_filter() eBPF/SO_ATTACH_FILTER drop\n - th->syn && th->fin discard in tcp_rcv_state_process() TCP_LISTEN\n - psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv()\n - tcp_checksum_complete() in tcp_v{4,6}_do_rcv()\n - tcp_v{4,6}_cookie_check() returning NULL\n\nWhen a packet is dropped on any of these paths, tcp_tw_isn is left set.\n\nThe next SYN processed on the same CPU then consumes the non zero value in\ntcp_conn_request(), receiving a potentially predictable ISN.\n\nThis patch moves back tcp_tw_isn to skb->cb[], getting rid of the per-cpu\nvariable.\n\nNote that tcp_v{4,6}_fill_cb() do not set it.\n\nVery litle impact on overall code size/complexity:\n\n$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new\nadd/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7)\nFunction                                     old     new   delta\ntcp_v6_rcv                                  3038    3042      +4\ntcp_v4_rcv                                  3035    3039      +4\ntcp_conn_request                            2938    2923     -15\nTotal: Before=24436060, After=24436053, chg -0.00%"}],"metrics":[{"cvssV3_1":{"baseScore":9.4,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-07-20T13:42:28.932Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/e47f7060eaf60894e3e4d0e3c4fe6e1f2eacfbdd"},{"url":"https://git.kernel.org/stable/c/4affe063fa56c880cbea8d0bfded0bb80751579d"},{"url":"https://git.kernel.org/stable/c/1bbf0ced1d9db73ac7893c2187f3459288603e0d"}],"title":"tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64024","datePublished":"2026-07-19T15:39:16.598Z","dateReserved":"2026-07-19T07:54:57.027Z","dateUpdated":"2026-07-20T13:42:28.932Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:17:42","lastModifiedDate":"2026-07-20 15:17:03","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H","baseScore":9.4,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.5}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64024","Ordinal":"1","Title":"tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction","CVE":"CVE-2026-64024","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64024","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction\n\nBlamed commit moved the TIME_WAIT-derived ISN from the skb control\nblock to a per-CPU variable, assuming the value would always be consumed\nby tcp_conn_request() for the same packet that wrote it. That assumption\nis violated by multiple drop paths between the producer\n(__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer\n(tcp_conn_request()):\n\n - min_ttl / min_hopcount check\n - xfrm policy check\n - tcp_inbound_hash() MD5/AO mismatch\n - tcp_filter() eBPF/SO_ATTACH_FILTER drop\n - th->syn && th->fin discard in tcp_rcv_state_process() TCP_LISTEN\n - psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv()\n - tcp_checksum_complete() in tcp_v{4,6}_do_rcv()\n - tcp_v{4,6}_cookie_check() returning NULL\n\nWhen a packet is dropped on any of these paths, tcp_tw_isn is left set.\n\nThe next SYN processed on the same CPU then consumes the non zero value in\ntcp_conn_request(), receiving a potentially predictable ISN.\n\nThis patch moves back tcp_tw_isn to skb->cb[], getting rid of the per-cpu\nvariable.\n\nNote that tcp_v{4,6}_fill_cb() do not set it.\n\nVery litle impact on overall code size/complexity:\n\n$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new\nadd/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7)\nFunction                                     old     new   delta\ntcp_v6_rcv                                  3038    3042      +4\ntcp_v4_rcv                                  3035    3039      +4\ntcp_conn_request                            2938    2923     -15\nTotal: Before=24436060, After=24436053, chg -0.00%","Type":"Description","Title":"tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction"}]}}}