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CVE-1999-1306

Status: ModifiedHigh (7.5)—
Severity7.5High · CVSS 2.0
Exploitation probability1.39 %higher than 72% of CVEs
Active exploitationNonot in the CISA catalog
Public exploitNot knownno public code found

Cisco IOS 9.1 and earlier does not properly handle extended IP access lists when the IP route cache is enabled and the "established" keyword is set, which could allow attackers to bypass filters.

CVSS

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

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days
1.39 %
Percentile among all scored CVEs
72
Score date
10/23/2026

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

References

Show 2 references

Raw JSON (NVD)

Show
{
  "id": "CVE-1999-1306",
  "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": "1992-12-10T05:00:00.000",
  "references": [
    {
      "url": "http://www.cert.org/advisories/CA-1992-20.html",
      "tags": [
        "Patch",
        "Third Party Advisory",
        "US Government Resource"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.cert.org/advisories/CA-1992-20.html",
      "tags": [
        "Patch",
        "Third Party Advisory",
        "US Government Resource"
      ],
      "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": "Cisco IOS 9.1 and earlier does not properly handle extended IP access lists when the IP route cache is enabled and the \"established\" keyword is set, which could allow attackers to bypass filters."
    }
  ],
  "lastModified": "2026-06-16T21:50:09.570",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:cisco:ios:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "91986F0D-94E5-4ED9-A98D-123C99FD43CE",
              "versionEndIncluding": "9.1"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@mitre.org"
}