ipv4: raw: reject IP_HDRINCL packets with ihl < 5
Summary
| CVE | CVE-2026-64114 |
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| State | PUBLISHED |
|---|
| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-07-19 16:17:52 UTC |
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| Updated | 2026-07-19 16:17:52 UTC |
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| Description | 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. |
|---|
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 1065b9efa4126df559b03a849c139ecfae92cd25 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 bc20dbd48c26e743f7e0845020c11ed2ce8b15ee git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 5a564f737ec54d63e8ee221d3ff396d07586d464 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 3c5411fa4944ed99af3d9d1de750ea8169b6dac9 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 145e9afa5b905229b4788bb72c3255f5a5f77508 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 7725cd3b471740fd23d25ed1da722c671fb2a5d3 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 bbe0be67de296176e7243c76e3d9f02f6ae9ff0b git |
Not specified |
| CNA |
Linux |
Linux |
affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 915fab69823a14c170dbaa3b41978768e0fe62fc git |
Not specified |
| CNA |
Linux |
Linux |
affected 2.6.12 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 2.6.12 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 5.10.258 5.10.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 5.15.209 5.15.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.1.175 6.1.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.6.142 6.6.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.92 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.34 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.0.11 7.0.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.1 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/1065b9efa4126df559b03a849c139ecfae92cd25 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/bc20dbd48c26e743f7e0845020c11ed2ce8b15ee |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/7725cd3b471740fd23d25ed1da722c671fb2a5d3 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/915fab69823a14c170dbaa3b41978768e0fe62fc |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/bbe0be67de296176e7243c76e3d9f02f6ae9ff0b |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/3c5411fa4944ed99af3d9d1de750ea8169b6dac9 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/5a564f737ec54d63e8ee221d3ff396d07586d464 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/145e9afa5b905229b4788bb72c3255f5a5f77508 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.
