ubuntu-cve-2025-66418
Vulnerability from osv_ubuntu
Published
2025-12-05 16:15
Modified
2026-05-29 10:28
Summary
Details

urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.

Severity
8.9 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "1.25.8-2ubuntu0.4+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@1.25.8-2ubuntu0.4+esm2?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.8-2ubuntu0.4+esm2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.24.1-1ubuntu1",
        "1.24.1-1ubuntu2",
        "1.25.8-1",
        "1.25.8-2",
        "1.25.8-2ubuntu0.1",
        "1.25.8-2ubuntu0.2",
        "1.25.8-2ubuntu0.3",
        "1.25.8-2ubuntu0.4",
        "1.25.8-2ubuntu0.4+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "1.26.5-1~exp1ubuntu0.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@1.26.5-1~exp1ubuntu0.4?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.26.5-1~exp1ubuntu0.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.26.5-1~exp1",
        "1.26.5-1~exp1ubuntu0.1",
        "1.26.5-1~exp1ubuntu0.2",
        "1.26.5-1~exp1ubuntu0.3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "python3-pip",
            "binary_version": "22.0.2+dfsg-1ubuntu0.7+esm1"
          },
          {
            "binary_name": "python3-pip-whl",
            "binary_version": "22.0.2+dfsg-1ubuntu0.7+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "python-pip",
        "purl": "pkg:deb/ubuntu/python-pip@22.0.2+dfsg-1ubuntu0.7+esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "22.0.2+dfsg-1ubuntu0.7+esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "20.3.4-4",
        "21.3.1+dfsg-3",
        "22.0.2+dfsg-1",
        "22.0.2+dfsg-1ubuntu0.1",
        "22.0.2+dfsg-1ubuntu0.2",
        "22.0.2+dfsg-1ubuntu0.3",
        "22.0.2+dfsg-1ubuntu0.4",
        "22.0.2+dfsg-1ubuntu0.5",
        "22.0.2+dfsg-1ubuntu0.6",
        "22.0.2+dfsg-1ubuntu0.7"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "2.0.7-1ubuntu0.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@2.0.7-1ubuntu0.3?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.7-1ubuntu0.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.26.16-1",
        "1.26.18-1",
        "2.0.7-1",
        "2.0.7-1ubuntu0.1",
        "2.0.7-1ubuntu0.2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "python3-pip",
            "binary_version": "24.0+dfsg-1ubuntu1.3+esm1"
          },
          {
            "binary_name": "python3-pip-whl",
            "binary_version": "24.0+dfsg-1ubuntu1.3+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "python-pip",
        "purl": "pkg:deb/ubuntu/python-pip@24.0+dfsg-1ubuntu1.3+esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "24.0+dfsg-1ubuntu1.3+esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "23.2+dfsg-1",
        "23.3+dfsg-1",
        "24.0+dfsg-1",
        "24.0+dfsg-1ubuntu1",
        "24.0+dfsg-1ubuntu1.1",
        "24.0+dfsg-1ubuntu1.2",
        "24.0+dfsg-1ubuntu1.3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-pip",
            "binary_version": "25.1.1+dfsg-1ubuntu2"
          },
          {
            "binary_name": "python3-pip-whl",
            "binary_version": "25.1.1+dfsg-1ubuntu2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "python-pip",
        "purl": "pkg:deb/ubuntu/python-pip@25.1.1+dfsg-1ubuntu2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "25.0+dfsg-1",
        "25.1.1+dfsg-1",
        "25.1.1+dfsg-1ubuntu1",
        "25.1.1+dfsg-1ubuntu2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "2.3.0-3ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@2.3.0-3ubuntu0.1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.0-3ubuntu0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.0-2",
        "2.3.0-2ubuntu1",
        "2.3.0-3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "2.5.0-1ubuntu1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@2.5.0-1ubuntu1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.5.0-1ubuntu1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.0-3",
        "2.5.0-1"
      ]
    }
  ],
  "aliases": [],
  "details": "urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.",
  "id": "UBUNTU-CVE-2025-66418",
  "modified": "2026-05-29T10:28:42Z",
  "published": "2025-12-05T16:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-66418"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-66418"
    },
    {
      "type": "REPORT",
      "url": "https://www.openwall.com/lists/oss-security/2025/12/05/4"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-7927-1"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8010-1"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8344-1"
    }
  ],
  "related": [
    "USN-7927-1",
    "USN-8010-1",
    "USN-8344-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-66418"
  ]
}



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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

Author Source Type Date Other

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.