{"id":"CVE-2026-64422","summary":"net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes","details":"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-\u003ereordering` 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.","modified":"2026-08-18T03:30:53.874452379Z","published":"2026-07-25T08:51:00.671Z","related":["openSUSE-SU-2026:11476-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64422.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98"},{"type":"WEB","url":"https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae"},{"type":"WEB","url":"https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64422.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64422"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf"},{"fixed":"f0d88a4cd03affff6c08adf6c63964e235aede43"},{"fixed":"27ddf4486c7dbf5bdd393fa8bef6b67179796d98"},{"fixed":"782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae"},{"fixed":"e81f805824a8109504fce090641b17d135b48cd1"},{"fixed":"99206ce2244f8a3ed64298d0667c9055845a5dc7"},{"fixed":"bbae351c0f32f7c200249e4aa6561b2b419dcf69"},{"fixed":"a094ac95d3b69adfa1676eb9c8eae6835d4f1671"},{"fixed":"efb8763d7bbb40cff4cc55a6b62c3095a038149c"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64422.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.24"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64422.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H"}]}