{"id":"CVE-2026-64114","title":"ipv4: raw: reject IP_HDRINCL packets with ihl < 5","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: raw: reject IP_HDRINCL packets with ihl < 5\n\nraw_send_hdrinc() validates that the caller-supplied IPv4 header\nfits within the message length:\n\n    iphlen = iph->i…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1065b9efa4126df559b03a849c139ecfae92cd25","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < bc20dbd48c26e743f7e0845020c11ed2ce8b15ee","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5a564f737ec54d63e8ee221d3ff396d07586d464","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3c5411fa4944ed99af3d9d1de750ea8169b6dac9","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 145e9afa5b905229b4788bb72c3255f5a5f77508","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7725cd3b471740fd23d25ed1da722c671fb2a5d3","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < bbe0be67de296176e7243c76e3d9f02f6ae9ff0b","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 915fab69823a14c170dbaa3b41978768e0fe62fc","Linux 2.6.12"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:36:31.414892Z"},"published":"2026-07-19","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:42:22.975Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64114","references":[{"url":"https://git.kernel.org/stable/c/1065b9efa4126df559b03a849c139ecfae92cd25"},{"url":"https://git.kernel.org/stable/c/bc20dbd48c26e743f7e0845020c11ed2ce8b15ee"},{"url":"https://git.kernel.org/stable/c/5a564f737ec54d63e8ee221d3ff396d07586d464"},{"url":"https://git.kernel.org/stable/c/3c5411fa4944ed99af3d9d1de750ea8169b6dac9"},{"url":"https://git.kernel.org/stable/c/145e9afa5b905229b4788bb72c3255f5a5f77508"},{"url":"https://git.kernel.org/stable/c/7725cd3b471740fd23d25ed1da722c671fb2a5d3"},{"url":"https://git.kernel.org/stable/c/bbe0be67de296176e7243c76e3d9f02f6ae9ff0b"},{"url":"https://git.kernel.org/stable/c/915fab69823a14c170dbaa3b41978768e0fe62fc"}],"tags":["cve.org"],"epss":0.00136,"epssPercentile":0.02675,"ingestedAt":"2026-10-16T17:24:46.806Z","slug":"CVE-2026-64114","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nipv4: raw: reject IP_HDRINCL packets with ihl < 5\n\nraw_send_hdrinc() validates that the caller-supplied IPv4 header\nfits within the message length:\n\n    iphlen = iph->ihl * 4;\n    err = -EINVAL;\n    if (iphlen > length)\n        goto error_free;\n\n    if (iphlen >= sizeof(*iph)) {\n        /* fix up saddr, tot_len, id, csum, transport_header */\n    }\n\nIt does not, however, reject ihl < 5.  For such a packet the\n\"if (iphlen >= sizeof(*iph))\" branch is skipped, leaving the\ncrafted iphdr untouched, but the packet is still handed to\n__ip_local_out() and onward.  Downstream consumers that read\niph->ihl assume a sane value: net/ipv4/ah4.c:ah_output() in\nparticular subtracts sizeof(struct iphdr) from top_iph->ihl * 4\nand passes the (signed-int-negative, then cast to size_t)\nresult to memcpy(), producing an OOB access of length close to\nSIZE_MAX and a host kernel panic.\n\nAn IPv4 header with ihl < 5 is malformed by definition (RFC 791:\n\"Internet Header Length is the length of the internet header in\n32 bit words ... Note that the minimum value for a correct header\nis 5.\").  The kernel should not be willing to inject such a\npacket into its own output path.\n\nReject \"iphlen < sizeof(*iph)\" alongside the existing\n\"iphlen > length\" check.  This matches the principle that locally\nconstructed packets that re-enter the IP stack must pass the same\nbasic sanity tests that a foreign packet would be subjected to.\n\nOnce this lands, the \"if (iphlen >= sizeof(*iph))\" wrapper around\nthe fixup branch becomes redundant; left in place to keep the\npatch minimal and backport-friendly.  A follow-up can unwrap it.\n\nNote that commit 86f4c90a1c5c (\"ipv4, ipv6: ensure raw socket\nmessage is big enough to hold an IP header\") ensures the message\nbuffer is large enough to hold an iphdr, but does not constrain\nthe self-reported iph->ihl.\n\nReachability: the malformed packet source is any caller with\nCAP_NET_RAW, including an unprivileged process in a user+net\nnamespace on a kernel with CONFIG_USER_NS=y.  The reproduced AH\ncrash also requires a matching xfrm AH policy on the outgoing\nroute; a container granted CAP_NET_ADMIN can install that state\nand policy in its netns.  Loopback bypasses xfrm_output, so the\ntrigger uses a real netdev.\n\nReproduced on UML + KASAN: kernel-mode fault at addr 0x0 with\nmemcpy_orig at the crash site.  Same shape reproduces inside a\nrootless Docker container with --cap-add NET_ADMIN on a stock\ndistro kernel.\n\n## Affected\n\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1065b9efa4126df559b03a849c139ecfae92cd25`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < bc20dbd48c26e743f7e0845020c11ed2ce8b15ee`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5a564f737ec54d63e8ee221d3ff396d07586d464`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3c5411fa4944ed99af3d9d1de750ea8169b6dac9`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 145e9afa5b905229b4788bb72c3255f5a5f77508`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7725cd3b471740fd23d25ed1da722c671fb2a5d3`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < bbe0be67de296176e7243c76e3d9f02f6ae9ff0b`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 915fab69823a14c170dbaa3b41978768e0fe62fc`\n- `Linux 2.6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}