CVE-2005-4437

Status: ModifiedHigh (7.5)—

MD5 Neighbor Authentication in Extended Interior Gateway Routing Protocol (EIGRP) 1.2, as implemented in Cisco IOS 11.3 and later, does not include the Message Authentication Code (MAC) in the checksum, which allows remote attackers to sniff message hashes and (1) replay EIGRP HELLO messages or (2) cause a denial of service by sending a large number of spoofed EIGRP neighbor announcements, which results in an ARP storm on the local network.

CVSS

Version: 2.0
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P
Base score: 7.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 2.39%
Percentile among all scored CVEs: 83
Score date: 10/7/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Extended Interior Gateway Routing Protocol — Extended Interior Gateway Routing Protocol

CWEs

NVD-CWE-Other

References

Raw JSON (NVD)

Show

{
  "id": "CVE-2005-4437",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 7.5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "LOW",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 6.4,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ]
  },
  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2005-12-21T01:03:00.000",
  "references": [
    {
      "url": "http://lists.grok.org.uk/pipermail/full-disclosure/2005-December/040332.html",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://marc.info/?l=full-disclosure&m=113504451523186&w=2",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://securityreason.com/securityalert/274",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://securitytracker.com/id?1015382",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.securityfocus.com/archive/1/419830/100/0/threaded",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.securityfocus.com/archive/1/419898/100/0/threaded",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.securityfocus.com/bid/15970",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.vupen.com/english/advisories/2005/3008",
      "source": "cve@mitre.org"
    },
    {
      "url": "https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5741",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://lists.grok.org.uk/pipermail/full-disclosure/2005-December/040332.html",
      "tags": [
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://marc.info/?l=full-disclosure&m=113504451523186&w=2",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://securityreason.com/securityalert/274",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://securitytracker.com/id?1015382",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.securityfocus.com/archive/1/419830/100/0/threaded",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.securityfocus.com/archive/1/419898/100/0/threaded",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.securityfocus.com/bid/15970",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.vupen.com/english/advisories/2005/3008",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5741",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "MD5 Neighbor Authentication in Extended Interior Gateway Routing Protocol (EIGRP) 1.2, as implemented in Cisco IOS 11.3 and later, does not include the Message Authentication Code (MAC) in the checksum, which allows remote attackers to sniff message hashes and (1) replay EIGRP HELLO messages or (2) cause a denial of service by sending a large number of spoofed EIGRP neighbor announcements, which results in an ARP storm on the local network."
    }
  ],
  "lastModified": "2026-06-16T22:18:47.727",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:extended_interior_gateway_routing_protocol:extended_interior_gateway_routing_protocol:1.2:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "77E7830C-3505-41C5-B073-D2F73261CE17"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@mitre.org"
}