{
  "document": {
    "acknowledgments": [
      {
        "summary": "This vulnerability was found during internal security testing."
      }
    ],
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "notes": [
      {
        "category": "summary",
        "text": "A vulnerability in the ingress traffic manager of Cisco IOS XE Software for Cisco Network Convergence System (NCS) 520 Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition in the web management interface of an affected device.\r\n\r\nThis vulnerability is due to incorrect processing of certain IPv4 TCP traffic that is destined to an affected device. An attacker could exploit this vulnerability by sending a large number of crafted TCP packets to the affected device. A successful exploit could allow the attacker to cause the web management interface to become unavailable, resulting in a DoS condition.\r\n\r\nNote: This vulnerability does not impact traffic that is going through the device or going to the Management Ethernet interface of the device.\r\n\r\nCisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.\r\n\r\n",
        "title": "Summary"
      },
      {
        "category": "general",
        "text": "At the time of publication, this vulnerability affected Cisco NCS 520 Routers if they were running a vulnerable release of Cisco IOS XE Software and had the HTTP server enabled.\r\n\r\nFor information about which Cisco software releases are vulnerable, see the Fixed Software [\"#fs\"] section of this advisory.\r\n    Determine the HTTP Server Configuration\r\nTo determine whether the HTTP Server feature is enabled for a device, log in to the device and use the show running-config | include ip http server|secure|active command in the CLI to check for the presence of the ip http server command or the ip http secure-server command in the global configuration. If either command is present and configured, the HTTP Server feature is enabled for the device.\r\n\r\nThe following example shows the output of the show running-config | include ip http server|secure|active command for a device that has the HTTP Server feature enabled:\r\n\r\n\r\nRouter# show running-config | include ip http server|secure|active\r\nip http server\r\nip http secure-server\r\n\r\nNote: The presence of either command or both commands in the device configuration indicates that the web UI feature is enabled.\r\n\r\nIf the ip http server command is present and the configuration also contains ip http active-session-modules none, the vulnerability is not exploitable over HTTP.\r\n\r\nIf the ip http secure-server command is present and the configuration also contains ip http secure-active-session-modules none, the vulnerability is not exploitable over HTTPS.",
        "title": "Vulnerable Products"
      },
      {
        "category": "general",
        "text": "Only products listed in the Vulnerable Products [\"#vp\"] section of this advisory are known to be affected by this vulnerability.\r\n\r\nCisco has confirmed that this vulnerability does not affect the following Cisco products:\r\n\r\nIOS Software\r\nIOS XR Software\r\nNX-OS Software",
        "title": "Products Confirmed Not Vulnerable"
      },
      {
        "category": "general",
        "text": "There are no workarounds that address this vulnerability.",
        "title": "Workarounds"
      },
      {
        "category": "general",
        "text": "When considering software upgrades [\"https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes\"], customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page [\"https://www.cisco.com/go/psirt\"], to determine exposure and a complete upgrade solution.\r\n\r\nIn all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.\r\n        Cisco IOS and IOS XE Software\r\nTo help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides the Cisco Software Checker [\"https://sec.cloudapps.cisco.com/security/center/softwarechecker.x\"] to identify any Cisco Security Advisories that impact a specific software release and the earliest release that fixes the vulnerabilities described in each advisory (\u201cFirst Fixed\u201d). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories identified (\u201cCombined First Fixed\u201d).\r\n\r\nCustomers can use the Cisco Software Checker [\"https://sec.cloudapps.cisco.com/security/center/softwarechecker.x\"] to search advisories in the following ways:\r\n\r\nChoose the software and one or more releases\r\nUpload a .txt file that includes a list of specific releases\r\nEnter the output of the show version command\r\n\r\nAfter initiating a search, customers can customize the search to include all Cisco Security Advisories, a specific advisory, or all advisories in the most recent bundled publication.\r\n\r\nCustomers can also use the following form to determine whether a release is affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE Software release\u2014for example, 15.1(4)M2 or 3.13.8S:\r\n\r\n\r\n\r\nBy default, the Cisco Software Checker [\"https://sec.cloudapps.cisco.com/security/center/softwarechecker.x\"] includes results only for vulnerabilities that have a Critical or High Security Impact Rating (SIR). To include results for Medium SIR vulnerabilities, customers can use the Cisco Software Checker on Cisco.com and check the Medium check box in the drop-down list under Impact Rating when customizing a search.\r\n\r\nFor a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to the Cisco IOS XE 2 Release Notes [\"https://www.cisco.com/c/en/us/td/docs/ios/ios_xe/2/release/notes/rnasr21/rnasr21_gen.html#wp3000032\"], Cisco IOS XE 3S Release Notes [\"https://www.cisco.com/c/en/us/td/docs/ios/ios_xe/3/release/notes/asr1k_rn_3s_rel_notes/asr1k_rn_3s_sys_req.html#wp3069754\"], or Cisco IOS XE 3SG Release Notes [\"https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/release/note/OL_24726.html#pgfId-2570252\"], depending on the Cisco IOS XE Software release.",
        "title": "Fixed Software"
      },
      {
        "category": "general",
        "text": "To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy [\"https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html\"]. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.",
        "title": "Vulnerability Policy"
      },
      {
        "category": "general",
        "text": "The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.",
        "title": "Exploitation and Public Announcements"
      },
      {
        "category": "general",
        "text": "This vulnerability was found during internal security testing.",
        "title": "Source"
      },
      {
        "category": "legal_disclaimer",
        "text": "THIS DOCUMENT IS PROVIDED ON AN \"AS IS\" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.\r\n\r\nA standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products.",
        "title": "Legal Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "psirt@cisco.com",
      "issuing_authority": "Cisco PSIRT",
      "name": "Cisco",
      "namespace": "https://wwww.cisco.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "Cisco IOS XE Software for Network Convergence System 520 Routers Denial of Service Vulnerability",
        "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ncs520-tcp-ZpzzOxB"
      },
      {
        "category": "external",
        "summary": "Cisco Security Vulnerability Policy",
        "url": "https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html"
      },
      {
        "category": "external",
        "summary": "considering software upgrades",
        "url": "https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes"
      },
      {
        "category": "external",
        "summary": "Cisco\u0026nbsp;Security Advisories page",
        "url": "https://www.cisco.com/go/psirt"
      },
      {
        "category": "external",
        "summary": "Cisco\u0026nbsp;Software Checker",
        "url": "https://sec.cloudapps.cisco.com/security/center/softwarechecker.x"
      },
      {
        "category": "external",
        "summary": "Cisco\u0026nbsp;IOS XE 2 Release Notes",
        "url": "https://www.cisco.com/c/en/us/td/docs/ios/ios_xe/2/release/notes/rnasr21/rnasr21_gen.html#wp3000032"
      },
      {
        "category": "external",
        "summary": "Cisco\u0026nbsp;IOS XE 3S Release Notes",
        "url": "https://www.cisco.com/c/en/us/td/docs/ios/ios_xe/3/release/notes/asr1k_rn_3s_rel_notes/asr1k_rn_3s_sys_req.html#wp3069754"
      },
      {
        "category": "external",
        "summary": "Cisco\u0026nbsp;IOS XE 3SG Release Notes",
        "url": "https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/release/note/OL_24726.html#pgfId-2570252"
      }
    ],
    "title": "Cisco IOS XE Software for Network Convergence System 520 Routers Denial of Service Vulnerability",
    "tracking": {
      "current_release_date": "2021-03-24T16:00:00+00:00",
      "generator": {
        "date": "2024-05-10T23:00:43+00:00",
        "engine": {
          "name": "TVCE"
        }
      },
      "id": "cisco-sa-ncs520-tcp-ZpzzOxB",
      "initial_release_date": "2021-03-24T16:00:00+00:00",
      "revision_history": [
        {
          "date": "2021-03-10T19:55:23+00:00",
          "number": "1.0.0",
          "summary": "Initial public release."
        }
      ],
      "status": "final",
      "version": "1.0.0"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "branches": [
                  {
                    "category": "service_pack",
                    "name": "16.10.1",
                    "product": {
                      "name": "16.10.1",
                      "product_id": "CSAFPID-225858"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1a",
                    "product": {
                      "name": "16.10.1a",
                      "product_id": "CSAFPID-250629"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1b",
                    "product": {
                      "name": "16.10.1b",
                      "product_id": "CSAFPID-252045"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1s",
                    "product": {
                      "name": "16.10.1s",
                      "product_id": "CSAFPID-252913"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1c",
                    "product": {
                      "name": "16.10.1c",
                      "product_id": "CSAFPID-254688"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1e",
                    "product": {
                      "name": "16.10.1e",
                      "product_id": "CSAFPID-257955"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1d",
                    "product": {
                      "name": "16.10.1d",
                      "product_id": "CSAFPID-258900"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1f",
                    "product": {
                      "name": "16.10.1f",
                      "product_id": "CSAFPID-262595"
                    }
                  },
                  {
                    "category": "service_pack",
                    "name": "16.10.1g",
                    "product": {
                      "name": "16.10.1g",
                      "product_id": "CSAFPID-266259"
                    }
                  }
                ],
                "category": "product_version",
                "name": "16.10"
              },
              {
                "branches": [
                  {
                    "category": "service_pack",
                    "name": "17.2.1v",
                    "product": {
                      "name": "17.2.1v",
                      "product_id": "CSAFPID-278002"
                    }
                  }
                ],
                "category": "product_version",
                "name": "17.2"
              }
            ],
            "category": "product_family",
            "name": "Cisco IOS XE Software"
          }
        ],
        "category": "vendor",
        "name": "Cisco"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-1394",
      "ids": [
        {
          "system_name": "Cisco Bug ID",
          "text": "CSCvm96192"
        }
      ],
      "notes": [
        {
          "category": "other",
          "text": "Complete.",
          "title": "Affected Product Comprehensiveness"
        }
      ],
      "product_status": {
        "known_affected": [
          "CSAFPID-225858",
          "CSAFPID-250629",
          "CSAFPID-252045",
          "CSAFPID-252913",
          "CSAFPID-254688",
          "CSAFPID-257955",
          "CSAFPID-258900",
          "CSAFPID-262595",
          "CSAFPID-266259",
          "CSAFPID-278002"
        ]
      },
      "release_date": "2021-03-24T16:00:00+00:00",
      "remediations": [
        {
          "category": "vendor_fix",
          "details": "Cisco has released software updates that address this vulnerability.",
          "product_ids": [
            "CSAFPID-225858",
            "CSAFPID-250629",
            "CSAFPID-252045",
            "CSAFPID-252913",
            "CSAFPID-254688",
            "CSAFPID-257955",
            "CSAFPID-258900",
            "CSAFPID-262595",
            "CSAFPID-266259",
            "CSAFPID-278002"
          ],
          "url": "https://software.cisco.com"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-225858",
            "CSAFPID-250629",
            "CSAFPID-252045",
            "CSAFPID-252913",
            "CSAFPID-254688",
            "CSAFPID-257955",
            "CSAFPID-258900",
            "CSAFPID-262595",
            "CSAFPID-266259",
            "CSAFPID-278002"
          ]
        }
      ],
      "title": "Cisco IOS XE Software TCP Denial of Service Vulnerability"
    }
  ]
}