ubuntu-cve-2021-1236
Vulnerability from osv_ubuntu
Published
2021-01-13 22:15
Modified
2025-10-24 04:49
Summary
Details

Multiple Cisco products are affected by a vulnerability in the Snort application detection engine that could allow an unauthenticated, remote attacker to bypass the configured policies on an affected system. The vulnerability is due to a flaw in the detection algorithm. An attacker could exploit this vulnerability by sending crafted packets that would flow through an affected system. A successful exploit could allow the attacker to bypass the configured policies and deliver a malicious payload to the protected network.

Severity
4.0 (Medium)
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "snort",
            "binary_version": "2.9.6.0-0ubuntu1"
          },
          {
            "binary_name": "snort-common",
            "binary_version": "2.9.6.0-0ubuntu1"
          },
          {
            "binary_name": "snort-common-libraries",
            "binary_version": "2.9.6.0-0ubuntu1"
          },
          {
            "binary_name": "snort-rules-default",
            "binary_version": "2.9.6.0-0ubuntu1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:14.04:LTS",
        "name": "snort",
        "purl": "pkg:deb/ubuntu/snort@2.9.6.0-0ubuntu1?arch=source\u0026distro=trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.9.2.2-3",
        "2.9.5.3-3",
        "2.9.6.0-0ubuntu1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "snort",
            "binary_version": "2.9.7.0-5"
          },
          {
            "binary_name": "snort-common",
            "binary_version": "2.9.7.0-5"
          },
          {
            "binary_name": "snort-common-libraries",
            "binary_version": "2.9.7.0-5"
          },
          {
            "binary_name": "snort-rules-default",
            "binary_version": "2.9.7.0-5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "snort",
        "purl": "pkg:deb/ubuntu/snort@2.9.7.0-5?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.9.7.0-5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "snort",
            "binary_version": "2.9.7.0-5build1"
          },
          {
            "binary_name": "snort-common",
            "binary_version": "2.9.7.0-5build1"
          },
          {
            "binary_name": "snort-common-libraries",
            "binary_version": "2.9.7.0-5build1"
          },
          {
            "binary_name": "snort-rules-default",
            "binary_version": "2.9.7.0-5build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "snort",
        "purl": "pkg:deb/ubuntu/snort@2.9.7.0-5build1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.9.7.0-5",
        "2.9.7.0-5build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "snort",
            "binary_version": "2.9.7.0-5build1"
          },
          {
            "binary_name": "snort-common",
            "binary_version": "2.9.7.0-5build1"
          },
          {
            "binary_name": "snort-common-libraries",
            "binary_version": "2.9.7.0-5build1"
          },
          {
            "binary_name": "snort-rules-default",
            "binary_version": "2.9.7.0-5build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "snort",
        "purl": "pkg:deb/ubuntu/snort@2.9.7.0-5build1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.9.7.0-5build1"
      ]
    }
  ],
  "aliases": [],
  "details": "Multiple Cisco products are affected by a vulnerability in the Snort application detection engine that could allow an unauthenticated, remote attacker to bypass the configured policies on an affected system. The vulnerability is due to a flaw in the detection algorithm. An attacker could exploit this vulnerability by sending crafted packets that would flow through an affected system. A successful exploit could allow the attacker to bypass the configured policies and deliver a malicious payload to the protected network.",
  "id": "UBUNTU-CVE-2021-1236",
  "modified": "2025-10-24T04:49:08Z",
  "published": "2021-01-13T22:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-1236"
    },
    {
      "type": "REPORT",
      "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-app-bypass-cSBYCATq"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2021-1236"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2021-1236"
  ]
}



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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.
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  • 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.