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CVE-2026-74657

Estado: RecibidaSin puntuar—

In the Linux kernel, the following vulnerability has been resolved:

ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops

fib_nlmsg_size() still estimates nexthop space as if every gateway is encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an IPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA.

As a result, route notifications can allocate an skb that is too small. fib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the WARN_ON() that marks such failures as a fib_nlmsg_size() bug. With panic_on_warn set, this becomes a kernel panic.

Mirror the actual nexthop dump layout in fib_nlmsg_size(): account for IPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop layout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is actually present.

CVSS

NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-74657",
  "cveTags": [],
  "metrics": {},
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "version": "d15662682db232da77136cd348f4c9df312ca6f9",
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          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
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              "version": "5.2"
            },
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              "version": "0",
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              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.10.267",
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            },
            {
              "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",
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              "status": "unaffected",
              "version": "7.1.9",
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            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/ipv4/fib_semantics.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-22T16:16:39.333",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0f0ca602941d0a81ae9514943ca06c55159c6385",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/7f80ad373ce4a7af5367ff273cea0f16e91387f3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/9b22f13524fa0de0d963bbd3002df6c28bae3395",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops\n\nfib_nlmsg_size() still estimates nexthop space as if every gateway is\nencoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an\nIPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA.\n\nAs a result, route notifications can allocate an skb that is too small.\nfib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the\nWARN_ON() that marks such failures as a fib_nlmsg_size() bug. With\npanic_on_warn set, this becomes a kernel panic.\n\nMirror the actual nexthop dump layout in fib_nlmsg_size(): account for\nIPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop\nlayout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is\nactually present."
    }
  ],
  "lastModified": "2026-08-27T13:18:36.153",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}