MSRC_CVE-2021-33503

Vulnerability from csaf_microsoft - Published: 2021-06-02 00:00 - Updated: 2021-12-16 00:00
Summary
An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.

Notes

Additional Resources
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
Disclaimer
The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
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{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2021-33503 An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect. - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-33503.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.",
    "tracking": {
      "current_release_date": "2021-12-16T00:00:00.000Z",
      "generator": {
        "date": "2025-10-19T22:02:44.746Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2021-33503",
      "initial_release_date": "2021-06-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2021-07-03T00:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2021-12-16T00:00:00.000Z",
          "legacy_version": "1.1",
          "number": "2",
          "summary": "Added python-urllib3 to CBL-Mariner 2.0"
        }
      ],
      "status": "final",
      "version": "2"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "1.0",
                "product": {
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                  "product_id": "16820"
                }
              },
              {
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                "name": "2.0",
                "product": {
                  "name": "CBL Mariner 2.0",
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                }
              },
              {
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                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
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                "product": {
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              },
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                "name": "cm1 python-urllib3 1.25.9-2",
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              },
              {
                "category": "product_version_range",
                "name": "\u003ccbl2 python-urllib3 1.25.9-3",
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              },
              {
                "category": "product_version",
                "name": "cbl2 python-urllib3 1.25.9-3",
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            }
          },
          {
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              "product_id": "1"
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          }
        ],
        "category": "vendor",
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      }
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    "relationships": [
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        "category": "default_component_of",
        "full_product_name": {
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        },
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  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-33503",
      "cwe": {
        "id": "CWE-400",
        "name": "Uncontrolled Resource Consumption"
      },
      "flags": [
        {
          "label": "component_not_present",
          "product_ids": [
            "17084-3"
          ]
        },
        {
          "label": "vulnerable_code_not_in_execute_path",
          "product_ids": [
            "17086-1"
          ]
        }
      ],
      "notes": [
        {
          "category": "general",
          "text": "mitre",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
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        ],
        "known_affected": [
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        ],
        "known_not_affected": [
          "17084-3",
          "17086-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2021-33503 An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect. - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-33503.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2021-07-03T00:00:00.000Z",
          "details": "1.25.9-2:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "16820-4"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        },
        {
          "category": "vendor_fix",
          "date": "2021-07-03T00:00:00.000Z",
          "details": "1.25.9-3:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "17086-2"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "environmentalsScore": 0.0,
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "temporalScore": 7.5,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "products": [
            "16820-4",
            "17086-2"
          ]
        }
      ],
      "title": "An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect."
    }
  ]
}


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  • 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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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