CVE-2012-3946

Status: ModifiedMedium (5)—

Cisco IOS before 15.3(2)S allows remote attackers to bypass interface ACL restrictions in opportunistic circumstances by sending IPv6 packets in an unspecified scenario in which expected packet drops do not occur for "a small percentage" of the packets, aka Bug ID CSCty73682.

CVSS

Version: 2.0
Vector: AV:N/AC:L/Au:N/C:P/I:N/A:N
Base score: 5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 1.93%
Percentile among all scored CVEs: 80
Score date: 10/19/2026

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)

Cisco — IOS

CWEs

CWE-264

References

Raw JSON (NVD)

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{
  "id": "CVE-2012-3946",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:P/I:N/A:N",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "LOW",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ]
  },
  "affected": [
    {
      "source": "psirt@cisco.com",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2014-04-24T10:55:02.290",
  "references": [
    {
      "url": "http://www.cisco.com/c/en/us/td/docs/ios/15_3s/release/notes/15_3s_rel_notes/15_3s_caveats_15_3_2s.html",
      "source": "psirt@cisco.com"
    },
    {
      "url": "http://www.cisco.com/c/en/us/td/docs/ios/15_3s/release/notes/15_3s_rel_notes/15_3s_caveats_15_3_2s.html",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-264"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Cisco IOS before 15.3(2)S allows remote attackers to bypass interface ACL restrictions in opportunistic circumstances by sending IPv6 packets in an unspecified scenario in which expected packet drops do not occur for \"a small percentage\" of the packets, aka Bug ID CSCty73682."
    },
    {
      "lang": "es",
      "value": "Cisco IOS anterior a 15.3(2)S permite a atacantes remotos evadir restricciones ACL de interfaz en circunstancias oportunistas mediante el envío de paquetes IPv6 en un escenario no especificado en que descargas de paquetes esperados no suceden para \"un porcentaje pequeño\" de los paquetes, también conocido como Bug ID CSCty73682."
    }
  ],
  "lastModified": "2026-06-16T23:44:06.567",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:cisco:ios:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "CFA52B1D-E3A2-4058-8B5C-DD862C39532B",
              "versionEndIncluding": "15.3"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "psirt@cisco.com"
}