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ubuntu-cve-2025-61920
Vulnerability from osv_ubuntu
Published
2025-10-10 20:15
Modified
2026-07-16 18:19
Summary
Details

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JOSE implementation accepts unbounded JWS/JWT header and signature segments. A remote attacker can craft a token whose base64url‑encoded header or signature spans hundreds of megabytes. During verification, Authlib decodes and parses the full input before it is rejected, driving CPU and memory consumption to hostile levels and enabling denial of service. Version 1.6.5 patches the issue. Some temporary workarounds are available. Enforce input size limits before handing tokens to Authlib and/or use application-level throttling to reduce amplification risk.

Severity
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: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "python3-authlib",
            "binary_version": "0.15.5-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "python-authlib",
        "purl": "pkg:deb/ubuntu/python-authlib@0.15.5-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.15.5-1ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.15.4-1",
        "0.15.5-1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "python3-authlib",
            "binary_version": "1.3.0-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "python-authlib",
        "purl": "pkg:deb/ubuntu/python-authlib@1.3.0-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.3.0-1ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.2.1-1",
        "1.3.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-authlib",
            "binary_version": "1.6.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "python-authlib",
        "purl": "pkg:deb/ubuntu/python-authlib@1.6.0-1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.5.1-1",
        "1.5.2-1",
        "1.6.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-authlib",
            "binary_version": "1.6.7-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:26.04:LTS",
        "name": "python-authlib",
        "purl": "pkg:deb/ubuntu/python-authlib@1.6.7-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.0-1",
        "1.6.5-1",
        "1.6.6-1",
        "1.6.7-1",
        "1.6.7-1ubuntu0.1~esm1"
      ]
    }
  ],
  "aliases": [],
  "details": "Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib\u2019s JOSE implementation accepts unbounded JWS/JWT header and signature segments. A remote attacker can craft a token whose base64url\u2011encoded header or signature spans hundreds of megabytes. During verification, Authlib decodes and parses the full input before it is rejected, driving CPU and memory consumption to hostile levels and enabling denial of service. Version 1.6.5 patches the issue. Some temporary workarounds are available. Enforce input size limits before handing tokens to Authlib and/or use application-level throttling to reduce amplification risk.",
  "id": "UBUNTU-CVE-2025-61920",
  "modified": "2026-07-16T18:19:35Z",
  "published": "2025-10-10T20:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-61920"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-61920"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/authlib/authlib/security/advisories/GHSA-pq5p-34cr-23v9"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/authlib/authlib/commit/867e3f87b072347a1ae9cf6983cc8bbf88447e5e"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/authlib/authlib/commit/867e3f87b072347a1ae9cf6983cc8bbf88447e5e"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8065-1"
    }
  ],
  "related": [
    "USN-8065-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "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-2025-61920"
  ]
}



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