ubuntu-cve-2021-45098
Vulnerability from osv_ubuntu
Published
2021-12-16 05:15
Modified
2025-10-24 04:50
Summary
Details

An issue was discovered in Suricata before 6.0.4. It is possible to bypass/evade any HTTP-based signature by faking an RST TCP packet with random TCP options of the md5header from the client side. After the three-way handshake, it's possible to inject an RST ACK with a random TCP md5header option. Then, the client can send an HTTP GET request with a forbidden URL. The server will ignore the RST ACK and send the response HTTP packet for the client's request. These packets will not trigger a Suricata reject action.

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

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "suricata",
            "binary_version": "3.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "suricata",
        "purl": "pkg:deb/ubuntu/suricata@3.0-1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.0.8-1build1",
        "2.0.9-1",
        "2.0.10-1",
        "2.0.10-2",
        "2.0.11-1",
        "3.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libhtp-0.5.23-1",
            "binary_version": "3.2-2ubuntu3"
          },
          {
            "binary_name": "suricata",
            "binary_version": "3.2-2ubuntu3"
          },
          {
            "binary_name": "suricata-hyperscan",
            "binary_version": "3.2-2ubuntu3"
          },
          {
            "binary_name": "suricata-oinkmaster",
            "binary_version": "3.2-2ubuntu3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "suricata",
        "purl": "pkg:deb/ubuntu/suricata@3.2-2ubuntu3?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.2-2ubuntu3"
      ]
    }
  ],
  "aliases": [],
  "details": "An issue was discovered in Suricata before 6.0.4. It is possible to bypass/evade any HTTP-based signature by faking an RST TCP packet with random TCP options of the md5header from the client side. After the three-way handshake, it\u0027s possible to inject an RST ACK with a random TCP md5header option. Then, the client can send an HTTP GET request with a forbidden URL. The server will ignore the RST ACK and send the response HTTP packet for the client\u0027s request. These packets will not trigger a Suricata reject action.",
  "id": "UBUNTU-CVE-2021-45098",
  "modified": "2025-10-24T04:50:38Z",
  "published": "2021-12-16T05:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-45098"
    },
    {
      "type": "REPORT",
      "url": "https://forum.suricata.io/t/suricata-6-0-4-and-5-0-8-released/1942"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/OISF/suricata/commit/50e2b973eeec7172991bf8f544ab06fb782b97df"
    },
    {
      "type": "REPORT",
      "url": "https://redmine.openinfosecfoundation.org/issues/4710"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/OISF/suricata/releases"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2021-45098"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2021-45098"
  ]
}



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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.
  • 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.