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ipv6: fix Route Information option length validation

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-74598

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-74598

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "2f6f94eda12430fb41b24b44a71e2ea4e93561d7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "7eac87396c44a312be457ef41d4c5687883be9a2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "7309529f257ae18e72112ef9f614edfd6df229bb",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "ff3cb05289b8a4ef95fa7ea14c7d34818359edbb",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "3b2231e358d26e3aec5d8040b1fb777af03c5f05",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "da64ed1f346ba84df574d6469fa2e422b2511719",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "70ceb4f53929f73746be72f73707cd9f8753e2fc",
        "lessThan": "d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv6/route.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "2.6.17"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "2.6.17",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.265",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.216",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.183",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.152",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.104",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.45",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.9",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv6/route.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74598

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#33232 · Revision 1
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Publisher date
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