{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74696", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.926Z", "datePublished": "2026-08-22T15:32:58.414Z", "dateUpdated": "2026-08-25T05:41:40.079Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-25T05:41:40.079Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix TFO max_qlen accounting across reuseport migration\n\nA listener's TCP_FASTOPEN max_qlen stops being accurate and lets through\nfar more pending Fast Open requests than it was configured for.\n\nThis only shows up with SO_REUSEPORT listener migration, where closing a\nlistener hands its still-pending TFO children over to a surviving one.\n\nfastopenq.qlen is charged in tcp_fastopen_create_child() when the child\nis created and uncharged in reqsk_fastopen_remove() when the handshake\ncompletes. The uncharge follows rsk_listener of the request the child\npoints at, and inet_reqsk_clone() has repointed the child at a new\nrequest owned by the new listener, so the ++ and the -- land on two\ndifferent sockets. The new listener's qlen drifts negative and its\nlimit no longer binds.\n\nCharge the new listener during migration, like reqsk_queue_migrated()\nalready does for queue->young and queue->qlen."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:N - The bug is in the inbound TCP SYN/TFO server path (tcp_v4_rcv/tcp_conn_request/tcp_try_fastopen), reachable by sending TCP Fast Open SYN packets to any internet-facing listener with server-side TFO enabled.\nAC:L - An attacker fully controls the TFO SYN flood; once a SO_REUSEPORT worker closes while TFO children are pending (routine nginx/k8s reloads), migration deterministically skews qlen negative with no narrow race or special memory layout required.\nPR:N - Exploitation needs only unauthenticated network reachability to the listening TCP port; no target credentials, capabilities, or local access are required because TFO SYN processing occurs before any application authentication.\nUI:N - No victim user action is needed beyond normal server operation; the remote attacker sends crafted TFO SYN traffic and benefits automatically when reuseport listener migration occurs during ordinary worker shutdown or reload.\nS:U - Impact is confined to the target host kernel TCP stack resource limits and availability; it does not cross VM, container, or IOMMU security boundaries to affect a different authority.\nC:N - The flaw is a signed counter accounting mismatch on fastopenq.qlen; it does not corrupt memory, leak kernel pointers, or provide an out-of-bounds read or use-after-free disclosure primitive.\nI:N - No arbitrary memory write, control-flow hijack, or unauthorized persistent data modification occurs; bypassing max_qlen only relaxes a rate limit while TFO cookie validation and normal TCP semantics still govern accepted data.\nA:H - With max_qlen disabled, a remote attacker can create far more pending TFO child sockets and SYN-carrying skbs than configured, exhausting kernel memory and socket tables and causing severe denial of service or OOM-induced host instability."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv4/inet_connection_sock.c"], "versions": [{"version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "lessThan": "e98f0d80b9cccb5f828425d2004f9686e7d1ae24", "status": "affected", "versionType": "git"}, {"version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "lessThan": "b6247e0f96bd825ffb2005257f6177b5e642dee6", "status": "affected", "versionType": "git"}, {"version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "lessThan": "585fc5247d14939a561056aa2addd9b7c2b1f670", "status": "affected", "versionType": "git"}, {"version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "lessThan": "6e10ee56524a26b250229ad348637825646ddb88", "status": "affected", "versionType": "git"}, {"version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "lessThan": "a66e869cf0c90c1e47ae75f72b6482acbfc808ff", "status": "affected", "versionType": "git"}, {"version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "lessThan": "d974618b2097453778389d385e3741629c40e0a3", "status": "affected", "versionType": "git"}, {"version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "lessThan": "a0ab2ba83e35159d81cec830a92e885ecf8139be", "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/ipv4/inet_connection_sock.c"], "versions": [{"version": "5.14", "status": "affected"}, {"version": "0", "lessThan": "5.14", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.152", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.104", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.45", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.9", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "5.14", "versionEndExcluding": "5.15.216"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.1.183"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.6.152"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.12.104"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.18.45"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "7.1.9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24"}, {"url": "https://git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6"}, {"url": "https://git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670"}, {"url": "https://git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88"}, {"url": "https://git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff"}, {"url": "https://git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3"}, {"url": "https://git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be"}], "title": "tcp: fix TFO max_qlen accounting across reuseport migration", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/ipv4/inet_connection_sock.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "e98f0d80b9cccb5f828425d2004f9686e7d1ae24", "status": "affected", "version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "versionType": "git"}, {"lessThan": "b6247e0f96bd825ffb2005257f6177b5e642dee6", "status": "affected", "version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "versionType": "git"}, {"lessThan": "585fc5247d14939a561056aa2addd9b7c2b1f670", "status": "affected", "version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "versionType": "git"}, {"lessThan": "6e10ee56524a26b250229ad348637825646ddb88", "status": "affected", "version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "versionType": "git"}, {"lessThan": "a66e869cf0c90c1e47ae75f72b6482acbfc808ff", "status": "affected", "version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "versionType": "git"}, {"lessThan": "d974618b2097453778389d385e3741629c40e0a3", "status": "affected", "version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "versionType": "git"}, {"lessThan": "a0ab2ba83e35159d81cec830a92e885ecf8139be", "status": "affected", "version": "54b92e84193749c9968aff2dd46e3b0f42643e18", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/ipv4/inet_connection_sock.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.14"}, {"lessThan": "5.14", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.216", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.183", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.152", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.104", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.45", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.9", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix TFO max_qlen accounting across reuseport migration\n\nA listener's TCP_FASTOPEN max_qlen stops being accurate and lets through\nfar more pending Fast Open requests than it was configured for.\n\nThis only shows up with SO_REUSEPORT listener migration, where closing a\nlistener hands its still-pending TFO children over to a surviving one.\n\nfastopenq.qlen is charged in tcp_fastopen_create_child() when the child\nis created and uncharged in reqsk_fastopen_remove() when the handshake\ncompletes. The uncharge follows rsk_listener of the request the child\npoints at, and inet_reqsk_clone() has repointed the child at a new\nrequest owned by the new listener, so the ++ and the -- land on two\ndifferent sockets. The new listener's qlen drifts negative and its\nlimit no longer binds.\n\nCharge the new listener during migration, like reqsk_queue_migrated()\nalready does for queue->young and queue->qlen."}], "id": "CVE-2026-74696", "lastModified": "2026-08-25T06:18:53.137", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-22T16:16:44.153", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: tcp: fix TFO max_qlen accounting across reuseport migration", "id": "2521430", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2521430"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-191", "details": ["In the Linux kernel, the following vulnerability has been resolved:\ntcp: fix TFO max_qlen accounting across reuseport migration\nA listener's TCP_FASTOPEN max_qlen stops being accurate and lets through\nfar more pending Fast Open requests than it was configured for.\nThis only shows up with SO_REUSEPORT listener migration, where closing a\nlistener hands its still-pending TFO children over to a surviving one.\nfastopenq.qlen is charged in tcp_fastopen_create_child() when the child\nis created and uncharged in reqsk_fastopen_remove() when the handshake\ncompletes. The uncharge follows rsk_listener of the request the child\npoints at, and inet_reqsk_clone() has repointed the child at a new\nrequest owned by the new listener, so the ++ and the -- land on two\ndifferent sockets. The new listener's qlen drifts negative and its\nlimit no longer binds.\nCharge the new listener during migration, like reqsk_queue_migrated()\nalready does for queue->young and queue->qlen.", "A flaw was found in the Linux kernel's TCP Fast Open (TFO) implementation. During SO_REUSEPORT listener migration, the system incorrectly accounts for pending TCP Fast Open requests. This can lead to a Denial of Service (DoS) by allowing an excessive number of Fast Open requests, potentially exhausting system resources."], "name": "CVE-2026-74696", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-22T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74696\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74696\nhttps://lore.kernel.org/linux-cve-announce/2026082234-CVE-2026-74696-3187@gregkh/T"], "threat_severity": "Moderate"}