{"api_version":"1","generated_at":"2026-07-23T15:34:51+00:00","cve":"CVE-2025-39955","urls":{"html":"https://cve.report/CVE-2025-39955","api":"https://cve.report/api/cve/CVE-2025-39955.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2025-39955","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-39955"},"summary":{"title":"tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().\n\nsyzbot reported the splat below where a socket had tcp_sk(sk)->fastopen_rsk\nin the TCP_ESTABLISHED state. [0]\n\nsyzbot reused the server-side TCP Fast Open socket as a new client before\nthe TFO socket completes 3WHS:\n\n  1. accept()\n  2. connect(AF_UNSPEC)\n  3. connect() to another destination\n\nAs of accept(), sk->sk_state is TCP_SYN_RECV, and tcp_disconnect() changes\nit to TCP_CLOSE and makes connect() possible, which restarts timers.\n\nSince tcp_disconnect() forgot to clear tcp_sk(sk)->fastopen_rsk, the\nretransmit timer triggered the warning and the intended packet was not\nretransmitted.\n\nLet's call reqsk_fastopen_remove() in tcp_disconnect().\n\n[0]:\nWARNING: CPU: 2 PID: 0 at net/ipv4/tcp_timer.c:542 tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))\nModules linked in:\nCPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.17.0-rc5-g201825fb4278 #62 PREEMPT(voluntary)\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\nRIP: 0010:tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))\nCode: 41 55 41 54 55 53 48 8b af b8 08 00 00 48 89 fb 48 85 ed 0f 84 55 01 00 00 0f b6 47 12 3c 03 74 0c 0f b6 47 12 3c 04 74 04 90 <0f> 0b 90 48 8b 85 c0 00 00 00 48 89 ef 48 8b 40 30 e8 6a 4f 06 3e\nRSP: 0018:ffffc900002f8d40 EFLAGS: 00010293\nRAX: 0000000000000002 RBX: ffff888106911400 RCX: 0000000000000017\nRDX: 0000000002517619 RSI: ffffffff83764080 RDI: ffff888106911400\nRBP: ffff888106d5c000 R08: 0000000000000001 R09: ffffc900002f8de8\nR10: 00000000000000c2 R11: ffffc900002f8ff8 R12: ffff888106911540\nR13: ffff888106911480 R14: ffff888106911840 R15: ffffc900002f8de0\nFS:  0000000000000000(0000) GS:ffff88907b768000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f8044d69d90 CR3: 0000000002c30003 CR4: 0000000000370ef0\nCall Trace:\n <IRQ>\n tcp_write_timer (net/ipv4/tcp_timer.c:738)\n call_timer_fn (kernel/time/timer.c:1747)\n __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2372)\n timer_expire_remote (kernel/time/timer.c:2385 kernel/time/timer.c:2376 kernel/time/timer.c:2135)\n tmigr_handle_remote_up (kernel/time/timer_migration.c:944 kernel/time/timer_migration.c:1035)\n __walk_groups.isra.0 (kernel/time/timer_migration.c:533 (discriminator 1))\n tmigr_handle_remote (kernel/time/timer_migration.c:1096)\n handle_softirqs (./arch/x86/include/asm/jump_label.h:36 ./include/trace/events/irq.h:142 kernel/softirq.c:580)\n irq_exit_rcu (kernel/softirq.c:614 kernel/softirq.c:453 kernel/softirq.c:680 kernel/softirq.c:696)\n sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1050 (discriminator 35) arch/x86/kernel/apic/apic.c:1050 (discriminator 35))\n </IRQ>","state":"PUBLISHED","assigner":"Linux","published_at":"2025-10-09 10:15:36","updated_at":"2026-07-14 13:17:51"},"problem_types":["NVD-CWE-noinfo"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}}],"references":[{"url":"https://git.kernel.org/stable/c/dfd06131107e7b699ef1e2a24ed2f7d17c917753","name":"https://git.kernel.org/stable/c/dfd06131107e7b699ef1e2a24ed2f7d17c917753","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/33a4fdf0b4a25f8ce65380c3b0136b407ca57609","name":"https://git.kernel.org/stable/c/33a4fdf0b4a25f8ce65380c3b0136b407ca57609","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/17d699727577814198d744d6afe54735c6b54c99","name":"https://git.kernel.org/stable/c/17d699727577814198d744d6afe54735c6b54c99","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ae313d14b45eca7a6bb29cb9bf396d977e7d28fb","name":"https://git.kernel.org/stable/c/ae313d14b45eca7a6bb29cb9bf396d977e7d28fb","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","name":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","refsource":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7ec092a91ff351dcde89c23e795b73a328274db6","name":"https://git.kernel.org/stable/c/7ec092a91ff351dcde89c23e795b73a328274db6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a4378dedd6e07e62f2fccb17d78c9665718763d0","name":"https://git.kernel.org/stable/c/a4378dedd6e07e62f2fccb17d78c9665718763d0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01","name":"https://git.kernel.org/stable/c/45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fa4749c065644af4db496b338452a69a3e5147d9","name":"https://git.kernel.org/stable/c/fa4749c065644af4db496b338452a69a3e5147d9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-39955","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39955","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 7ec092a91ff351dcde89c23e795b73a328274db6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 a4378dedd6e07e62f2fccb17d78c9665718763d0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 33a4fdf0b4a25f8ce65380c3b0136b407ca57609 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 17d699727577814198d744d6afe54735c6b54c99 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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custom","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2025","cve_id":"39955","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2025-39955","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","timestamp":"2026-06-10T20:41:49.740642Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-06-11T18:44:16.576Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"},{"affected":[{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]},{"defaultStatus":"unknown","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]}],"providerMetadata":{"dateUpdated":"2026-07-14T12:43:08.999Z","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","shortName":"siemens-SADP"},"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html"}],"x_adpType":"supplier"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/ipv4/tcp.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"7ec092a91ff351dcde89c23e795b73a328274db6","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"},{"lessThan":"a4378dedd6e07e62f2fccb17d78c9665718763d0","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"},{"lessThan":"33a4fdf0b4a25f8ce65380c3b0136b407ca57609","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"},{"lessThan":"17d699727577814198d744d6afe54735c6b54c99","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"},{"lessThan":"dfd06131107e7b699ef1e2a24ed2f7d17c917753","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"},{"lessThan":"fa4749c065644af4db496b338452a69a3e5147d9","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"},{"lessThan":"ae313d14b45eca7a6bb29cb9bf396d977e7d28fb","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"},{"lessThan":"45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01","status":"affected","version":"8336886f786fdacbc19b719c1f7ea91eb70706d4","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ipv4/tcp.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"3.7"},{"lessThan":"3.7","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.4.*","status":"unaffected","version":"5.4.300","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.245","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.194","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.154","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.108","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.49","versionType":"semver"},{"lessThanOrEqual":"6.16.*","status":"unaffected","version":"6.16.9","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"6.17","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.4.300","versionStartIncluding":"3.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.245","versionStartIncluding":"3.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.194","versionStartIncluding":"3.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.154","versionStartIncluding":"3.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.108","versionStartIncluding":"3.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.49","versionStartIncluding":"3.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.16.9","versionStartIncluding":"3.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.17","versionStartIncluding":"3.7","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().\n\nsyzbot reported the splat below where a socket had tcp_sk(sk)->fastopen_rsk\nin the TCP_ESTABLISHED state. [0]\n\nsyzbot reused the server-side TCP Fast Open socket as a new client before\nthe TFO socket completes 3WHS:\n\n  1. accept()\n  2. connect(AF_UNSPEC)\n  3. connect() to another destination\n\nAs of accept(), sk->sk_state is TCP_SYN_RECV, and tcp_disconnect() changes\nit to TCP_CLOSE and makes connect() possible, which restarts timers.\n\nSince tcp_disconnect() forgot to clear tcp_sk(sk)->fastopen_rsk, the\nretransmit timer triggered the warning and the intended packet was not\nretransmitted.\n\nLet's call reqsk_fastopen_remove() in tcp_disconnect().\n\n[0]:\nWARNING: CPU: 2 PID: 0 at net/ipv4/tcp_timer.c:542 tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))\nModules linked in:\nCPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.17.0-rc5-g201825fb4278 #62 PREEMPT(voluntary)\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\nRIP: 0010:tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))\nCode: 41 55 41 54 55 53 48 8b af b8 08 00 00 48 89 fb 48 85 ed 0f 84 55 01 00 00 0f b6 47 12 3c 03 74 0c 0f b6 47 12 3c 04 74 04 90 <0f> 0b 90 48 8b 85 c0 00 00 00 48 89 ef 48 8b 40 30 e8 6a 4f 06 3e\nRSP: 0018:ffffc900002f8d40 EFLAGS: 00010293\nRAX: 0000000000000002 RBX: ffff888106911400 RCX: 0000000000000017\nRDX: 0000000002517619 RSI: ffffffff83764080 RDI: ffff888106911400\nRBP: ffff888106d5c000 R08: 0000000000000001 R09: ffffc900002f8de8\nR10: 00000000000000c2 R11: ffffc900002f8ff8 R12: ffff888106911540\nR13: ffff888106911480 R14: ffff888106911840 R15: ffffc900002f8de0\nFS:  0000000000000000(0000) GS:ffff88907b768000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f8044d69d90 CR3: 0000000002c30003 CR4: 0000000000370ef0\nCall Trace:\n <IRQ>\n tcp_write_timer (net/ipv4/tcp_timer.c:738)\n call_timer_fn (kernel/time/timer.c:1747)\n __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2372)\n timer_expire_remote (kernel/time/timer.c:2385 kernel/time/timer.c:2376 kernel/time/timer.c:2135)\n tmigr_handle_remote_up (kernel/time/timer_migration.c:944 kernel/time/timer_migration.c:1035)\n __walk_groups.isra.0 (kernel/time/timer_migration.c:533 (discriminator 1))\n tmigr_handle_remote (kernel/time/timer_migration.c:1096)\n handle_softirqs (./arch/x86/include/asm/jump_label.h:36 ./include/trace/events/irq.h:142 kernel/softirq.c:580)\n irq_exit_rcu (kernel/softirq.c:614 kernel/softirq.c:453 kernel/softirq.c:680 kernel/softirq.c:696)\n sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1050 (discriminator 35) arch/x86/kernel/apic/apic.c:1050 (discriminator 35))\n </IRQ>"}],"providerMetadata":{"dateUpdated":"2026-05-11T21:39:39.433Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/7ec092a91ff351dcde89c23e795b73a328274db6"},{"url":"https://git.kernel.org/stable/c/a4378dedd6e07e62f2fccb17d78c9665718763d0"},{"url":"https://git.kernel.org/stable/c/33a4fdf0b4a25f8ce65380c3b0136b407ca57609"},{"url":"https://git.kernel.org/stable/c/17d699727577814198d744d6afe54735c6b54c99"},{"url":"https://git.kernel.org/stable/c/dfd06131107e7b699ef1e2a24ed2f7d17c917753"},{"url":"https://git.kernel.org/stable/c/fa4749c065644af4db496b338452a69a3e5147d9"},{"url":"https://git.kernel.org/stable/c/ae313d14b45eca7a6bb29cb9bf396d977e7d28fb"},{"url":"https://git.kernel.org/stable/c/45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01"}],"title":"tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2025-39955","datePublished":"2025-10-09T09:47:33.556Z","dateReserved":"2025-04-16T07:20:57.149Z","dateUpdated":"2026-07-14T12:43:08.999Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2025-10-09 10:15:36","lastModifiedDate":"2026-07-14 13:17:51","problem_types":["NVD-CWE-noinfo"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-06-10T20:41:49.740642Z","id":"CVE-2025-39955","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.7","versionEndExcluding":"5.4.300","matchCriteriaId":"EF3A9D25-ED48-454C-90BC-70C637BF3185"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.10.245","matchCriteriaId":"B0E443AF-02FC-45A1-9CD7-3F80A65F1A15"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.194","matchCriteriaId":"CF862263-DC8D-4324-A52A-DA1D7880B35A"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.1.154","matchCriteriaId":"E49CD91E-FC55-45B0-BB63-9AD5F5D70CAA"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.108","matchCriteriaId":"A7E8EAEE-7731-4996-9578-696255D61EA2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.49","matchCriteriaId":"CAA033E9-A2C5-4976-A83E-9804D8FB827F"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.16.9","matchCriteriaId":"638DD910-1189-4F5E-98BF-2D436B695112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*","matchCriteriaId":"327D22EF-390B-454C-BD31-2ED23C998A1C"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*","matchCriteriaId":"C730CD9A-D969-4A8E-9522-162AAF7C0EE9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*","matchCriteriaId":"39982C4B-716E-4B2F-8196-FA301F47807D"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*","matchCriteriaId":"340BEEA9-D70D-4290-B502-FBB1032353B1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:*","matchCriteriaId":"47E4C5C0-079F-4838-971B-8C503D48FCC2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:*","matchCriteriaId":"5A4516A6-C12E-42A4-8C0E-68AEF3264504"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2025","CveId":"39955","Ordinal":"1","Title":"tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().","CVE":"CVE-2025-39955","Year":"2025"},"notes":[{"CveYear":"2025","CveId":"39955","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().\n\nsyzbot reported the splat below where a socket had tcp_sk(sk)->fastopen_rsk\nin the TCP_ESTABLISHED state. [0]\n\nsyzbot reused the server-side TCP Fast Open socket as a new client before\nthe TFO socket completes 3WHS:\n\n  1. accept()\n  2. connect(AF_UNSPEC)\n  3. connect() to another destination\n\nAs of accept(), sk->sk_state is TCP_SYN_RECV, and tcp_disconnect() changes\nit to TCP_CLOSE and makes connect() possible, which restarts timers.\n\nSince tcp_disconnect() forgot to clear tcp_sk(sk)->fastopen_rsk, the\nretransmit timer triggered the warning and the intended packet was not\nretransmitted.\n\nLet's call reqsk_fastopen_remove() in tcp_disconnect().\n\n[0]:\nWARNING: CPU: 2 PID: 0 at net/ipv4/tcp_timer.c:542 tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))\nModules linked in:\nCPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.17.0-rc5-g201825fb4278 #62 PREEMPT(voluntary)\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\nRIP: 0010:tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7))\nCode: 41 55 41 54 55 53 48 8b af b8 08 00 00 48 89 fb 48 85 ed 0f 84 55 01 00 00 0f b6 47 12 3c 03 74 0c 0f b6 47 12 3c 04 74 04 90 <0f> 0b 90 48 8b 85 c0 00 00 00 48 89 ef 48 8b 40 30 e8 6a 4f 06 3e\nRSP: 0018:ffffc900002f8d40 EFLAGS: 00010293\nRAX: 0000000000000002 RBX: ffff888106911400 RCX: 0000000000000017\nRDX: 0000000002517619 RSI: ffffffff83764080 RDI: ffff888106911400\nRBP: ffff888106d5c000 R08: 0000000000000001 R09: ffffc900002f8de8\nR10: 00000000000000c2 R11: ffffc900002f8ff8 R12: ffff888106911540\nR13: ffff888106911480 R14: ffff888106911840 R15: ffffc900002f8de0\nFS:  0000000000000000(0000) GS:ffff88907b768000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f8044d69d90 CR3: 0000000002c30003 CR4: 0000000000370ef0\nCall Trace:\n <IRQ>\n tcp_write_timer (net/ipv4/tcp_timer.c:738)\n call_timer_fn (kernel/time/timer.c:1747)\n __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2372)\n timer_expire_remote (kernel/time/timer.c:2385 kernel/time/timer.c:2376 kernel/time/timer.c:2135)\n tmigr_handle_remote_up (kernel/time/timer_migration.c:944 kernel/time/timer_migration.c:1035)\n __walk_groups.isra.0 (kernel/time/timer_migration.c:533 (discriminator 1))\n tmigr_handle_remote (kernel/time/timer_migration.c:1096)\n handle_softirqs (./arch/x86/include/asm/jump_label.h:36 ./include/trace/events/irq.h:142 kernel/softirq.c:580)\n irq_exit_rcu (kernel/softirq.c:614 kernel/softirq.c:453 kernel/softirq.c:680 kernel/softirq.c:696)\n sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1050 (discriminator 35) arch/x86/kernel/apic/apic.c:1050 (discriminator 35))\n </IRQ>","Type":"Description","Title":"tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect()."}]}}}