CVE-2026-74598 (GCVE-0-2026-74598)
Vulnerability from cvelistv5
Published
2026-08-22 15:31
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ipv6: fix Route Information option length validation
rt6_route_rcv() validates the Route Information option (RFC 4191) length
against the prefix length, but both checks are off by one.
rinfo->length is the ND option length in units of 8 octets and it
*includes* the 8-byte option header, so an option carrying N bytes of
prefix has length == 1 + N/8. RFC 4191 section 2.3 requires length 3
when Prefix Length is greater than 64, and 2 or 3 when it is greater
than 0. The code accepts length >= 2 and length >= 1 respectively.
ipv6_addr_prefix() then copies prefix_len/8 bytes out of rinfo->prefix,
so a Router Advertisement with (prefix_len=128, length=2) or
(prefix_len=64, length=1) makes the kernel read up to 8 bytes past the
end of the option. Those bytes end up in the prefix of the route that
gets installed, so they are visible to userspace:
# RA with a Route Information option (prefix_len=128, length=2)
# followed by a source link-layer address option, 01 01 de ad be ef ca fe
$ ip -6 route show
2001:db8:dead:beef:101:dead:beef:cafe via fe80::1234 dev veth0 proto ra
^^^^^^^^^^^^^^^^^^ the next option, read out of bounds
When the Route Information option is the last one in the packet, those
eight bytes come from the skb tail room instead.
Reject the option lengths RFC 4191 does not allow.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc Version: 70ceb4f53929f73746be72f73707cd9f8753e2fc |
||
{
"containers": {
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"product": "Linux",
"programFiles": [
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"vendor": "Linux",
"versions": [
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"status": "unaffected",
"version": "0",
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},
{
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"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "5.15.216",
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},
{
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"status": "unaffected",
"version": "6.1.183",
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{
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"version": "6.6.152",
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{
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"version": "6.12.104",
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{
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"version": "7.1.9",
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{
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"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
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],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix Route Information option length validation\n\nrt6_route_rcv() validates the Route Information option (RFC 4191) length\nagainst the prefix length, but both checks are off by one.\n\nrinfo-\u003elength is the ND option length in units of 8 octets and it\n*includes* the 8-byte option header, so an option carrying N bytes of\nprefix has length == 1 + N/8. RFC 4191 section 2.3 requires length 3\nwhen Prefix Length is greater than 64, and 2 or 3 when it is greater\nthan 0. The code accepts length \u003e= 2 and length \u003e= 1 respectively.\n\nipv6_addr_prefix() then copies prefix_len/8 bytes out of rinfo-\u003eprefix,\nso a Router Advertisement with (prefix_len=128, length=2) or\n(prefix_len=64, length=1) makes the kernel read up to 8 bytes past the\nend of the option. Those bytes end up in the prefix of the route that\ngets installed, so they are visible to userspace:\n\n # RA with a Route Information option (prefix_len=128, length=2)\n # followed by a source link-layer address option, 01 01 de ad be ef ca fe\n $ ip -6 route show\n 2001:db8:dead:beef:101:dead:beef:cafe via fe80::1234 dev veth0 proto ra\n ^^^^^^^^^^^^^^^^^^ the next option, read out of bounds\n\nWhen the Route Information option is the last one in the packet, those\neight bytes come from the skb tail room instead.\n\nReject the option lengths RFC 4191 does not allow."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.5,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The flaw is reached from inbound ICMPv6 Router Advertisements on the standard IPv6 receive path (ip6_input\u2192icmpv6_rcv\u2192ndisc_rcv\u2192ndisc_router_discovery\u2192rt6_route_rcv), so a network peer can trigger it on hosts accepting RAs (phones, laptops, IoT, containers on shared L2).\nAC:L - Once the victim accepts non-zero Route Information prefixes, an attacker fully controls prefix_len and option length in forged RAs and can deterministically trigger the out-of-bounds read (up to 8 bytes) without races or uncontrollable memory layout.\nPR:N - Exploitation requires only sending crafted ICMPv6 RAs on the victim\u0027s link; the attacker needs no account, capabilities, or init-namespace root on the target, only the ability to inject ND traffic the host will process.\nUI:N - No victim user action is required beyond normal IPv6 connectivity; RA/Route Information processing runs automatically in the kernel when accept_ra and related sysctls permit it.\nS:U - Impact is confined to kernel IPv6 routing state leaking into the same host\u0027s userspace route table; it does not cross VM, container, or IOMMU security boundaries into a separate authority.\nC:H - ipv6_addr_prefix() performs an out-of-bounds read of up to eight bytes past the Route Information option (from following ND options or skb tailroom), and those kernel bytes are stored in the installed route prefix visible to userspace via netlink or ip -6 route.\nI:N - The bug is a bounded out-of-bounds read into a stack buffer followed by route installation; it does not corrupt kernel memory, enable arbitrary writes, or provide a demonstrated control-flow hijack primitive.\nA:N - The vulnerable path only mis-handles prefix extraction and installs a route with leaked bytes; it does not cause kernel oops, panic, hang, or demonstrated denial of service beyond incorrect route data."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:24.953Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/2f6f94eda12430fb41b24b44a71e2ea4e93561d7"
},
{
"url": "https://git.kernel.org/stable/c/7eac87396c44a312be457ef41d4c5687883be9a2"
},
{
"url": "https://git.kernel.org/stable/c/7309529f257ae18e72112ef9f614edfd6df229bb"
},
{
"url": "https://git.kernel.org/stable/c/0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d"
},
{
"url": "https://git.kernel.org/stable/c/ff3cb05289b8a4ef95fa7ea14c7d34818359edbb"
},
{
"url": "https://git.kernel.org/stable/c/3b2231e358d26e3aec5d8040b1fb777af03c5f05"
},
{
"url": "https://git.kernel.org/stable/c/da64ed1f346ba84df574d6469fa2e422b2511719"
},
{
"url": "https://git.kernel.org/stable/c/d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824"
}
],
"title": "ipv6: fix Route Information option length validation",
"x_generator": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74598",
"datePublished": "2026-08-22T15:31:47.859Z",
"dateReserved": "2026-08-15T05:44:03.919Z",
"dateUpdated": "2026-08-25T05:40:24.953Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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