CVE-2026-64114 (GCVE-0-2026-64114)
Vulnerability from cvelistv5
Published
2026-07-19 15:40
Modified
2026-10-19 20:28
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv4: raw: reject IP_HDRINCL packets with ihl < 5 raw_send_hdrinc() validates that the caller-supplied IPv4 header fits within the message length: iphlen = iph->ihl * 4; err = -EINVAL; if (iphlen > length) goto error_free; if (iphlen >= sizeof(*iph)) { /* fix up saddr, tot_len, id, csum, transport_header */ } It does not, however, reject ihl < 5. For such a packet the "if (iphlen >= sizeof(*iph))" branch is skipped, leaving the crafted iphdr untouched, but the packet is still handed to __ip_local_out() and onward. Downstream consumers that read iph->ihl assume a sane value: net/ipv4/ah4.c:ah_output() in particular subtracts sizeof(struct iphdr) from top_iph->ihl * 4 and passes the (signed-int-negative, then cast to size_t) result to memcpy(), producing an OOB access of length close to SIZE_MAX and a host kernel panic. An IPv4 header with ihl < 5 is malformed by definition (RFC 791: "Internet Header Length is the length of the internet header in 32 bit words ... Note that the minimum value for a correct header is 5."). The kernel should not be willing to inject such a packet into its own output path. Reject "iphlen < sizeof(*iph)" alongside the existing "iphlen > length" check. This matches the principle that locally constructed packets that re-enter the IP stack must pass the same basic sanity tests that a foreign packet would be subjected to. Once this lands, the "if (iphlen >= sizeof(*iph))" wrapper around the fixup branch becomes redundant; left in place to keep the patch minimal and backport-friendly. A follow-up can unwrap it. Note that commit 86f4c90a1c5c ("ipv4, ipv6: ensure raw socket message is big enough to hold an IP header") ensures the message buffer is large enough to hold an iphdr, but does not constrain the self-reported iph->ihl. Reachability: the malformed packet source is any caller with CAP_NET_RAW, including an unprivileged process in a user+net namespace on a kernel with CONFIG_USER_NS=y. The reproduced AH crash also requires a matching xfrm AH policy on the outgoing route; a container granted CAP_NET_ADMIN can install that state and policy in its netns. Loopback bypasses xfrm_output, so the trigger uses a real netdev. Reproduced on UML + KASAN: kernel-mode fault at addr 0x0 with memcpy_orig at the crash site. Same shape reproduces inside a rootless Docker container with --cap-add NET_ADMIN on a stock distro kernel.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: raw: reject IP_HDRINCL packets with ihl \u003c 5\n\nraw_send_hdrinc() validates that the caller-supplied IPv4 header\nfits within the message length:\n\n    iphlen = iph-\u003eihl * 4;\n    err = -EINVAL;\n    if (iphlen \u003e length)\n        goto error_free;\n\n    if (iphlen \u003e= sizeof(*iph)) {\n        /* fix up saddr, tot_len, id, csum, transport_header */\n    }\n\nIt does not, however, reject ihl \u003c 5.  For such a packet the\n\"if (iphlen \u003e= 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-\u003eihl assume a sane value: net/ipv4/ah4.c:ah_output() in\nparticular subtracts sizeof(struct iphdr) from top_iph-\u003eihl * 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 \u003c 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 \u003c sizeof(*iph)\" alongside the existing\n\"iphlen \u003e 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 \u003e= 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-\u003eihl.\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."
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              "value": "AV:L - Exploitation requires local syscalls (socket/sendmsg on a raw IP_HDRINCL socket); malformed packets are injected locally into the output path, not via remote network ingress which validates ihl \u003e= 5.\nAC:L - The attacker fully controls the crafted header ihl value and can install the required xfrm AH policy and route via CAP_NET_ADMIN in their own network namespace, making exploitation reliable without conditions outside attacker control.\nPR:L - Triggering requires CAP_NET_RAW for raw sockets and CAP_NET_ADMIN to install xfrm AH policy, both obtainable by an unprivileged user via user+network namespaces or a container granted NET_ADMIN without init-namespace root.\nUI:N - No victim interaction is required; the attacker sends the malformed packet directly through their own raw socket and configured IPsec policy.\nS:U - Impact is kernel memory corruption and panic within the same kernel security boundary; this is not a VM escape, sandbox escape, or cross-authority boundary violation.\nC:H - The integer underflow in ah_output() memcpy length produces an out-of-bounds read of near SIZE_MAX bytes, providing an arbitrary kernel memory read primitive beyond any bounded disclosure.\nI:H - The same memcpy with underflowed length causes a massive out-of-bounds write that can corrupt adjacent kernel heap memory and be leveraged for control-flow hijacking.\nA:H - The OOB memcpy reliably causes a kernel-mode fault and host panic, as reproduced with KASAN and in a rootless Docker container, denying all system availability."
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        "dateUpdated": "2026-08-05T12:39:23.263Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/1065b9efa4126df559b03a849c139ecfae92cd25"
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        {
          "url": "https://git.kernel.org/stable/c/bc20dbd48c26e743f7e0845020c11ed2ce8b15ee"
        },
        {
          "url": "https://git.kernel.org/stable/c/5a564f737ec54d63e8ee221d3ff396d07586d464"
        },
        {
          "url": "https://git.kernel.org/stable/c/3c5411fa4944ed99af3d9d1de750ea8169b6dac9"
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          "url": "https://git.kernel.org/stable/c/915fab69823a14c170dbaa3b41978768e0fe62fc"
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      "title": "ipv4: raw: reject IP_HDRINCL packets with ihl \u003c 5",
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    "cveId": "CVE-2026-64114",
    "datePublished": "2026-07-19T15:40:14.854Z",
    "dateReserved": "2026-07-19T07:54:57.035Z",
    "dateUpdated": "2026-10-19T20:28:12.671Z",
    "state": "PUBLISHED"
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      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-64114\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-16T15:36:31.414892Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-20\", \"description\": \"CWE-20 Improper Input Validation\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-10-16T15:36:32.087Z\"}}], \"cna\": {\"title\": \"ipv4: raw: reject IP_HDRINCL packets with ihl \u003c 5\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 7.8, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:L - Exploitation requires local syscalls (socket/sendmsg on a raw IP_HDRINCL socket); malformed packets are injected locally into the output path, not via remote network ingress which validates ihl \u003e= 5.\\nAC:L - The attacker fully controls the crafted header ihl value and can install the required xfrm AH policy and route via CAP_NET_ADMIN in their own network namespace, making exploitation reliable without conditions outside attacker control.\\nPR:L - Triggering requires CAP_NET_RAW for raw sockets and CAP_NET_ADMIN to install xfrm AH policy, both obtainable by an unprivileged user via user+network namespaces or a container granted NET_ADMIN without init-namespace root.\\nUI:N - No victim interaction is required; the attacker sends the malformed packet directly through their own raw socket and configured IPsec policy.\\nS:U - Impact is kernel memory corruption and panic within the same kernel security boundary; this is not a VM escape, sandbox escape, or cross-authority boundary violation.\\nC:H - The integer underflow in ah_output() memcpy length produces an out-of-bounds read of near SIZE_MAX bytes, providing an arbitrary kernel memory read primitive beyond any bounded disclosure.\\nI:H - The same memcpy with underflowed length causes a massive out-of-bounds write that can corrupt adjacent kernel heap memory and be leveraged for control-flow hijacking.\\nA:H - The OOB memcpy reliably causes a kernel-mode fault and host panic, as reproduced with KASAN and in a rootless Docker container, denying all system availability.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"1065b9efa4126df559b03a849c139ecfae92cd25\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"bc20dbd48c26e743f7e0845020c11ed2ce8b15ee\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"5a564f737ec54d63e8ee221d3ff396d07586d464\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"3c5411fa4944ed99af3d9d1de750ea8169b6dac9\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"145e9afa5b905229b4788bb72c3255f5a5f77508\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"7725cd3b471740fd23d25ed1da722c671fb2a5d3\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"bbe0be67de296176e7243c76e3d9f02f6ae9ff0b\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\", \"lessThan\": \"915fab69823a14c170dbaa3b41978768e0fe62fc\", \"versionType\": \"git\"}], \"programFiles\": [\"net/ipv4/raw.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.6.12\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"2.6.12\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.258\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.209\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.175\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.142\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.92\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.18.34\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"7.0.11\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"7.0.*\"}, {\"status\": \"unaffected\", \"version\": \"7.1\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/ipv4/raw.c\"], \"defaultStatus\": \"affected\"}], \"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\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nipv4: raw: reject IP_HDRINCL packets with ihl \u003c 5\\n\\nraw_send_hdrinc() validates that the caller-supplied IPv4 header\\nfits within the message length:\\n\\n    iphlen = iph-\u003eihl * 4;\\n    err = -EINVAL;\\n    if (iphlen \u003e length)\\n        goto error_free;\\n\\n    if (iphlen \u003e= sizeof(*iph)) {\\n        /* fix up saddr, tot_len, id, csum, transport_header */\\n    }\\n\\nIt does not, however, reject ihl \u003c 5.  For such a packet the\\n\\\"if (iphlen \u003e= 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-\u003eihl assume a sane value: net/ipv4/ah4.c:ah_output() in\\nparticular subtracts sizeof(struct iphdr) from top_iph-\u003eihl * 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 \u003c 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 \u003c sizeof(*iph)\\\" alongside the existing\\n\\\"iphlen \u003e 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 \u003e= 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-\u003eihl.\\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.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.258\", \"versionStartIncluding\": \"2.6.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.209\", \"versionStartIncluding\": \"2.6.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.175\", \"versionStartIncluding\": \"2.6.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.142\", \"versionStartIncluding\": \"2.6.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.92\", \"versionStartIncluding\": \"2.6.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.34\", \"versionStartIncluding\": \"2.6.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.0.11\", \"versionStartIncluding\": \"2.6.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.1\", \"versionStartIncluding\": \"2.6.12\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T12:39:23.263Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-64114\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T20:28:12.671Z\", \"dateReserved\": \"2026-07-19T07:54:57.035Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-07-19T15:40:14.854Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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