{ "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": "2026-08-17T04:55:22.159Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:55:22.159Z" }, "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’s 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’s 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, BUG, or kernel panic, and an attacker can trigger the path repeatedly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/sysctl_net_ipv4.c", "net/ipv4/tcp_output.c" ], "versions": [ { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "f0d88a4cd03affff6c08adf6c63964e235aede43", "status": "affected", "versionType": "git" }, { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "27ddf4486c7dbf5bdd393fa8bef6b67179796d98", "status": "affected", "versionType": "git" }, { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae", "status": "affected", "versionType": "git" }, { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "e81f805824a8109504fce090641b17d135b48cd1", "status": "affected", "versionType": "git" }, { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "99206ce2244f8a3ed64298d0667c9055845a5dc7", "status": "affected", "versionType": "git" }, { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "bbae351c0f32f7c200249e4aa6561b2b419dcf69", "status": "affected", "versionType": "git" }, { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "a094ac95d3b69adfa1676eb9c8eae6835d4f1671", "status": "affected", "versionType": "git" }, { "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf", "lessThan": "efb8763d7bbb40cff4cc55a6b62c3095a038149c", "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/sysctl_net_ipv4.c", "net/ipv4/tcp_output.c" ], "versions": [ { "version": "2.6.24", "status": "affected" }, { "version": "0", "lessThan": "2.6.24", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.261", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.96", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.39", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.4", "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": "2.6.24", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.24", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.24", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.24", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.24", "versionEndExcluding": "6.12.96" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.24", "versionEndExcluding": "6.18.39" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.24", "versionEndExcluding": "7.1.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.24", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43" }, { "url": "https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98" }, { "url": "https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae" }, { "url": "https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1" }, { "url": "https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7" }, { "url": "https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69" }, { "url": "https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671" }, { "url": "https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c" } ], "title": "net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes", 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