USN-7927-2 (UBUNTU-CVE-2025-66471)

Vulnerability from osv_ubuntu – Published: 2026-01-12 21:26 – Updated: 2026-04-27 14:11 – Source website
VLAI
Summary
python-urllib3 regression
Details

USN-7927-1 fixed vulnerabilities in urllib3. The update for CVE-2025-66471 introduced a regression in the zstd decompression component inside urllib3. This update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

Illia Volochii discovered that urllib3 did not limit the steps in a decompression chain. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. (CVE-2025-66418)

Rui Xi discovered that urllib3 incorrectly handled highly compressed data. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. (CVE-2025-66471)

For the brotli encoding, the fix for CVE-2025-66471 requires an additional security update in the brotli package.

References
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2025-66471",
              "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"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:24.04:LTS"
        }
      },
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "2.0.7-1ubuntu0.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@2.0.7-1ubuntu0.5?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.7-1ubuntu0.5"
            }
          ],
          "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",
        "2.0.7-1ubuntu0.3",
        "2.0.7-1ubuntu0.4"
      ]
    },
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2025-66471",
              "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"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:25.10"
        }
      },
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "2.3.0-3ubuntu0.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@2.3.0-3ubuntu0.3?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.0-3ubuntu0.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.0-2",
        "2.3.0-2ubuntu1",
        "2.3.0-3",
        "2.3.0-3ubuntu0.1",
        "2.3.0-3ubuntu0.2"
      ]
    }
  ],
  "aliases": [],
  "details": "USN-7927-1 fixed vulnerabilities in urllib3. The update for CVE-2025-66471\nintroduced a regression in the zstd decompression component inside urllib3.\nThis update fixes the problem.\n\nWe apologize for the inconvenience.\n\nOriginal advisory details:\n\n Illia Volochii discovered that urllib3 did not limit the steps in a\n decompression chain. An attacker could possibly use this issue to cause\n urllib3 to use excessive resources, causing a denial of service.\n (CVE-2025-66418)\n\n Rui Xi discovered that urllib3 incorrectly handled highly compressed data.\n An attacker could possibly use this issue to cause urllib3 to use\n excessive resources, causing a denial of service. This issue only affected\n Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. (CVE-2025-66471)\n\n For the brotli encoding, the fix for CVE-2025-66471 requires an additional\n security update in the brotli package.",
  "id": "USN-7927-2",
  "modified": "2026-04-27T14:11:47Z",
  "published": "2026-01-12T21:26:18Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-7927-2"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-66471"
    },
    {
      "type": "REPORT",
      "url": "https://launchpad.net/bugs/2136906"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "summary": "python-urllib3 regression",
  "upstream": [
    "UBUNTU-CVE-2025-66471"
  ]
}



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