CVE-2021-47109 (GCVE-0-2021-47109)

Vulnerability from cvelistv5 – Published: 2024-03-15 20:14 – Updated: 2026-08-05 08:46
VLAI
Title
neighbour: allow NUD_NOARP entries to be forced GCed
Summary
In the Linux kernel, the following vulnerability has been resolved: neighbour: allow NUD_NOARP entries to be forced GCed IFF_POINTOPOINT interfaces use NUD_NOARP entries for IPv6. It's possible to fill up the neighbour table with enough entries that it will overflow for valid connections after that. This behaviour is more prevalent after commit 58956317c8de ("neighbor: Improve garbage collection") is applied, as it prevents removal from entries that are not NUD_FAILED, unless they are more than 5s old.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-03-19 15:24 UTC
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 58956317c8de52009d1a38a721474c24aef74fe7 , < d99029e6aab62aef0a0251588b2867e77e83b137 (git)
Affected: 58956317c8de52009d1a38a721474c24aef74fe7 , < d17d47da59f726dc4c87caebda3a50333d7e2fd3 (git)
Affected: 58956317c8de52009d1a38a721474c24aef74fe7 , < ddf088d7aaaaacfc836104f2e632b29b1d383cfc (git)
Affected: 58956317c8de52009d1a38a721474c24aef74fe7 , < 7a6b1ab7475fd6478eeaf5c9d1163e7a18125c8f (git)
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Linux Linux Affected: 5.0
Unaffected: 0 , < 5.0 (semver)
Unaffected: 5.4.125 , ≤ 5.4.* (semver)
Unaffected: 5.10.43 , ≤ 5.10.* (semver)
Unaffected: 5.12.10 , ≤ 5.12.* (semver)
Unaffected: 5.13 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-08-05T03:22:41+00:00",
      "cve": "CVE-2021-47109",
      "id": "CVE-2021-47109",
      "initial_release_date": "2021-01-01T00:00:00+00:00",
      "product_status:known_affected": "42",
      "product_status:known_not_affected": "156",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: neighbour: allow NUD_NOARP entries to be forced GCed",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-47109.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-09T23:35:53Z",
      "cve": "CVE-2021-47109",
      "id": "CVE-2021-47109",
      "initial_release_date": "2024-03-19T03:50:27Z",
      "product_status:known_affected": "404",
      "product_status:known_not_affected": "301",
      "product_status:recommended": "137",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2021-47109",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2021-47109.json",
      "version": "41"
    },
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      "cveMetadata": "{\"cveId\": \"CVE-2021-47109\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T08:46:03.543Z\", \"dateReserved\": \"2024-03-04T18:12:48.836Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-03-15T20:14:18.469Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Taxonomy of the tags.





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.


Detection rules are retrieved from Rulezet.