CVE-2026-53012 (GCVE-0-2026-53012)

Vulnerability from cvelistv5 – Published: 2026-06-24 16:29 – Updated: 2026-06-24 16:29
VLAI
Title
nexthop: fix IPv6 route referencing IPv4 nexthop
Summary
In the Linux kernel, the following vulnerability has been resolved: nexthop: fix IPv6 route referencing IPv4 nexthop syzbot reported a panic [1] [2]. When an IPv6 nexthop is replaced with an IPv4 nexthop, the has_v4 flag of all groups containing this nexthop is not updated. This is because nh_group_v4_update is only called when replacing AF_INET to AF_INET6, but the reverse direction (AF_INET6 to AF_INET) is missed. This allows a stale has_v4=false to bypass fib6_check_nexthop, causing IPv6 routes to be attached to groups that effectively contain only AF_INET members. Subsequent route lookups then call nexthop_fib6_nh() which returns NULL for the AF_INET member, leading to a NULL pointer dereference. Fix by calling nh_group_v4_update whenever the family changes, not just AF_INET to AF_INET6. Reproducer: # AF_INET6 blackhole ip -6 nexthop add id 1 blackhole # group with has_v4=false ip nexthop add id 100 group 1 # replace with AF_INET (no -6), has_v4 stays false ip nexthop replace id 1 blackhole # pass stale has_v4 check ip -6 route add 2001:db8::/64 nhid 100 # panic ping -6 2001:db8::1 [1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0 [2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < ceffe81a0be92afc0cd1340bc8ca46559cce9bb4 (git)
Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < 9c2d6770a5f4545a307eb66979bef7656a34d621 (git)
Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < 6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8 (git)
Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < aaac3bed034239e1d75732211d9b05f30b0b4f35 (git)
Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < ad85961004fd4bd2f31209ac4b07612c6cefb9e7 (git)
Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < 613c8f4a501421dd258b07ea614205d4e16ec845 (git)
Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < b3b7e850e1541f0520c4a12ec884255c30427ff6 (git)
Affected: 7bf4796dd09984ad1612877a82d0d139c70ae27f , < 29c95185ba32b621fbc3800fb86e7dc3edf5c2be (git)
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Linux Linux Affected: 5.3
Unaffected: 0 , < 5.3 (semver)
Unaffected: 5.10.258 , ≤ 5.10.* (semver)
Unaffected: 5.15.209 , ≤ 5.15.* (semver)
Unaffected: 6.1.175 , ≤ 6.1.* (semver)
Unaffected: 6.6.141 , ≤ 6.6.* (semver)
Unaffected: 6.12.91 , ≤ 6.12.* (semver)
Unaffected: 6.18.33 , ≤ 6.18.* (semver)
Unaffected: 7.0.10 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: fix IPv6 route referencing IPv4 nexthop\n\nsyzbot reported a panic [1] [2].\n\nWhen an IPv6 nexthop is replaced with an IPv4 nexthop, the has_v4 flag\nof all groups containing this nexthop is not updated. This is because\nnh_group_v4_update is only called when replacing AF_INET to AF_INET6,\nbut the reverse direction (AF_INET6 to AF_INET) is missed.\n\nThis allows a stale has_v4=false to bypass fib6_check_nexthop, causing\nIPv6 routes to be attached to groups that effectively contain only AF_INET\nmembers. Subsequent route lookups then call nexthop_fib6_nh() which\nreturns NULL for the AF_INET member, leading to a NULL pointer\ndereference.\n\nFix by calling nh_group_v4_update whenever the family changes, not just\nAF_INET to AF_INET6.\n\nReproducer:\n\t# AF_INET6 blackhole\n\tip -6 nexthop add id 1 blackhole\n\t# group with has_v4=false\n\tip nexthop add id 100 group 1\n\t# replace with AF_INET (no -6), has_v4 stays false\n\tip nexthop replace id 1 blackhole\n\t# pass stale has_v4 check\n\tip -6 route add 2001:db8::/64 nhid 100\n\t# panic\n\tping -6 2001:db8::1\n\n[1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0\n[2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3"
        }
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      "providerMetadata": {
        "dateUpdated": "2026-06-24T16:29:22.973Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/ceffe81a0be92afc0cd1340bc8ca46559cce9bb4"
        },
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          "url": "https://git.kernel.org/stable/c/9c2d6770a5f4545a307eb66979bef7656a34d621"
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          "url": "https://git.kernel.org/stable/c/ad85961004fd4bd2f31209ac4b07612c6cefb9e7"
        },
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          "url": "https://git.kernel.org/stable/c/613c8f4a501421dd258b07ea614205d4e16ec845"
        },
        {
          "url": "https://git.kernel.org/stable/c/b3b7e850e1541f0520c4a12ec884255c30427ff6"
        },
        {
          "url": "https://git.kernel.org/stable/c/29c95185ba32b621fbc3800fb86e7dc3edf5c2be"
        }
      ],
      "title": "nexthop: fix IPv6 route referencing IPv4 nexthop",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53012",
    "datePublished": "2026-06-24T16:29:22.973Z",
    "dateReserved": "2026-06-09T07:44:35.378Z",
    "dateUpdated": "2026-06-24T16:29:22.973Z",
    "state": "PUBLISHED"
  },
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Subsequent route lookups then call nexthop_fib6_nh() which\\nreturns NULL for the AF_INET member, leading to a NULL pointer\\ndereference.\\n\\nFix by calling nh_group_v4_update whenever the family changes, not just\\nAF_INET to AF_INET6.\\n\\nReproducer:\\n\\t# AF_INET6 blackhole\\n\\tip -6 nexthop add id 1 blackhole\\n\\t# group with has_v4=false\\n\\tip nexthop add id 100 group 1\\n\\t# replace with AF_INET (no -6), has_v4 stays false\\n\\tip nexthop replace id 1 blackhole\\n\\t# pass stale has_v4 check\\n\\tip -6 route add 2001:db8::/64 nhid 100\\n\\t# panic\\n\\tping -6 2001:db8::1\\n\\n[1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0\\n[2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/ipv4/nexthop.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"ceffe81a0be92afc0cd1340bc8ca46559cce9bb4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"9c2d6770a5f4545a307eb66979bef7656a34d621\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"aaac3bed034239e1d75732211d9b05f30b0b4f35\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"ad85961004fd4bd2f31209ac4b07612c6cefb9e7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"613c8f4a501421dd258b07ea614205d4e16ec845\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"b3b7e850e1541f0520c4a12ec884255c30427ff6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7bf4796dd09984ad1612877a82d0d139c70ae27f\",\"lessThan\":\"29c95185ba32b621fbc3800fb86e7dc3edf5c2be\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/ipv4/nexthop.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.3\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.3\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.258\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.209\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.175\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.141\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.91\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.33\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.10\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/29c95185ba32b621fbc3800fb86e7dc3edf5c2be\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/613c8f4a501421dd258b07ea614205d4e16ec845\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9c2d6770a5f4545a307eb66979bef7656a34d621\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/aaac3bed034239e1d75732211d9b05f30b0b4f35\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ad85961004fd4bd2f31209ac4b07612c6cefb9e7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b3b7e850e1541f0520c4a12ec884255c30427ff6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ceffe81a0be92afc0cd1340bc8ca46559cce9bb4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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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

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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.


Detection rules are retrieved from Rulezet.