{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-64422", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.787Z", "datePublished": "2026-07-25T08:51:00.671Z", "dateUpdated": "2026-08-05T12:41:52.362Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:41:52.362Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv4: bound TCP reordering sysctl writes and MTU probe sizes\n\nReject invalid `net.ipv4.tcp_reordering` values before they reach TCP\nsocket state. The sysctl is stored as an `int` but copied into the\n`u32` `tp->reordering` field for new sockets, so negative writes wrap\nto large values.\n\nWith `tcp_mtu_probing=2`, the wrapped value can overflow the\n`tcp_mtu_probe()` size calculation and drive the MTU probing path into\nan out-of-bounds read. Route `tcp_reordering` writes through\n`proc_dointvec_minmax()` and require it to be at least 1. Also require\n`tcp_max_reordering` to be at least 1 so the configured maximum cannot\nbecome negative either.\n\nWhen registering the table for a non-init network namespace, relocate\n`extra2` pointers that refer into `init_net.ipv4` so the\n`tcp_reordering` upper bound follows that namespace's\n`tcp_max_reordering`.\n\nHarden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`.\nThis keeps the send queue and window checks from being bypassed through\nsigned integer overflow."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The attacker must locally write the per-network-namespace TCP sysctls and exercise a TCP socket; remote packets alone cannot introduce the invalid signed value.\nAC:L - The attacker can set both tcp_reordering and tcp_mtu_probing=2, establish an attacker-controlled TCP connection, grow its congestion window, and control queued data and receiver-window conditions.\nPR:L - Writes require CAP_NET_ADMIN in the network namespace\u2019s owning user namespace, which an unprivileged user can obtain by creating user and network namespaces on systems permitting unprivileged user namespaces.\nUI:N - The attacker can configure the namespace and trigger MTU probing using their own TCP endpoints without any victim action.\nS:U - The vulnerable TCP implementation and the affected kernel memory and availability remain within the Linux kernel\u2019s security authority.\nC:H - The overflow bypasses send-queue validation and causes an out-of-bounds kernel-memory read through an invalid skb traversal, potentially exposing sensitive kernel data.\nI:N - The established primitive is an out-of-bounds read and malformed skb state; the affected path provides no demonstrated out-of-bounds write or other data-modification primitive.\nA:H - The invalid skb access and inconsistent payload geometry can cause an OOPS, 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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/ipv4/sysctl_net_ipv4.c", "net/ipv4/tcp_output.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "f0d88a4cd03affff6c08adf6c63964e235aede43", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}, {"lessThan": "27ddf4486c7dbf5bdd393fa8bef6b67179796d98", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}, {"lessThan": "782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}, {"lessThan": "e81f805824a8109504fce090641b17d135b48cd1", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}, {"lessThan": "99206ce2244f8a3ed64298d0667c9055845a5dc7", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}, {"lessThan": "bbae351c0f32f7c200249e4aa6561b2b419dcf69", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}, {"lessThan": "a094ac95d3b69adfa1676eb9c8eae6835d4f1671", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}, {"lessThan": "efb8763d7bbb40cff4cc55a6b62c3095a038149c", "status": "affected", "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/ipv4/sysctl_net_ipv4.c", "net/ipv4/tcp_output.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "2.6.24"}, {"lessThan": "2.6.24", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.261", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.212", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.178", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.145", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.96", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.39", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2-rc1", "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\nnet: ipv4: bound TCP reordering sysctl writes and MTU probe sizes\n\nReject invalid `net.ipv4.tcp_reordering` values before they reach TCP\nsocket state. The sysctl is stored as an `int` but copied into the\n`u32` `tp->reordering` field for new sockets, so negative writes wrap\nto large values.\n\nWith `tcp_mtu_probing=2`, the wrapped value can overflow the\n`tcp_mtu_probe()` size calculation and drive the MTU probing path into\nan out-of-bounds read. Route `tcp_reordering` writes through\n`proc_dointvec_minmax()` and require it to be at least 1. Also require\n`tcp_max_reordering` to be at least 1 so the configured maximum cannot\nbecome negative either.\n\nWhen registering the table for a non-init network namespace, relocate\n`extra2` pointers that refer into `init_net.ipv4` so the\n`tcp_reordering` upper bound follows that namespace's\n`tcp_max_reordering`.\n\nHarden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`.\nThis keeps the send queue and window checks from being bypassed through\nsigned integer overflow."}], "id": "CVE-2026-64422", "lastModified": "2026-08-11T15:01:50.637", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-07-25T10:17:26.213", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Awaiting Analysis"}

{"bugzilla": {"description": "kernel: net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes", "id": "2507160", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2507160"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "details": ["A flaw was found in the Linux kernel's IPv4 networking stack. Invalid values for `net.ipv4.tcp_reordering`, particularly negative inputs, can lead to an integer overflow when processed. When `tcp_mtu_probing` is enabled, this overflow can cause an out-of-bounds read within the `tcp_mtu_probe()` function. This vulnerability may allow an attacker to access sensitive information or cause system instability."], "name": "CVE-2026-64422", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "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": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-07-25T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64422\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64422\nhttps://lore.kernel.org/linux-cve-announce/2026072534-CVE-2026-64422-d391@gregkh/T"], "threat_severity": "Moderate"}

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