FKIE_CVE-2026-74598
Vulnerability from fkie_nvd - Published: 2026-08-22 16:16 - Updated: 2026-08-25 06:18
Severity
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 |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv6/route.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "2f6f94eda12430fb41b24b44a71e2ea4e93561d7",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
},
{
"lessThan": "7eac87396c44a312be457ef41d4c5687883be9a2",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
},
{
"lessThan": "7309529f257ae18e72112ef9f614edfd6df229bb",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
},
{
"lessThan": "0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
},
{
"lessThan": "ff3cb05289b8a4ef95fa7ea14c7d34818359edbb",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
},
{
"lessThan": "3b2231e358d26e3aec5d8040b1fb777af03c5f05",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
},
{
"lessThan": "da64ed1f346ba84df574d6469fa2e422b2511719",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
},
{
"lessThan": "d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824",
"status": "affected",
"version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv6/route.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.17"
},
{
"lessThan": "2.6.17",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"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."
}
],
"id": "CVE-2026-74598",
"lastModified": "2026-08-25T06:18:35.740",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 3.6,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-22T16:16:32.170",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2f6f94eda12430fb41b24b44a71e2ea4e93561d7"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3b2231e358d26e3aec5d8040b1fb777af03c5f05"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7309529f257ae18e72112ef9f614edfd6df229bb"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7eac87396c44a312be457ef41d4c5687883be9a2"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/da64ed1f346ba84df574d6469fa2e422b2511719"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ff3cb05289b8a4ef95fa7ea14c7d34818359edbb"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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