Critical

joserfc — security advisory

Type: advisorySources: OSVAdvisory ID: UBUNTU-CVE-2025-65015

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions from 1.3.3 to before 1.3.5 and from 1.4.0 to before 1.4.2, the ExceededSizeError exception messages are embedded with non-decoded JWT token parts and may cause Python logging to record an arbitrarily large, forged JWT payload. In situations where a misconfigured — or entirely absent — production-grade web server sits in front of a Python web application, an attacker may be able to send arbitrarily large bearer tokens in the HTTP request headers. When this occurs, Python logging or diagnostic tools (e.g., Sentry) may end up processing extremely large log messages containing the full JWT header during the joserfc.jwt.decode() operation. The same behavior also appears when validating claims and signature payload sizes, as the library raises joserfc.errors.ExceededSizeError() with the full payload embedded in the exception message. Since the payload is already fully loaded into memory at this stage, the library cannot prevent or reject it. This issue has been patched in versions 1.3.5 and 1.4.2.

Products: joserfc
Affected versions: 1.0.4-1, 1.1.0-1, 1.2.0-1, 1.2.2-1, 1.4.0-1, 1.4.1-1, 1.4.3-1, 1.5.0-1, 1.6.2-1, 1.6.5-1, 1.6.8-1, 1.7.0-1, 1.7.1-1, 1.7.2-1, 1.7.4-1
Fixed versions: Not specified
CVEs: CVE-2025-65015
Confirmed fixed CVEs: Not specified
Updated in this feed: 31 Oct 2026, 02:33 UTC · Revision 1

Source evidence

UBUNTU-CVE-2025-65015

core-osv · Original source

Published 18 Nov 2025, 23:15 UTC

osv:UBUNTU-CVE-2025-65015

joserfc

Fixed versions: Not specified

joserfc

Fixed versions: Not specified

joserfc

Fixed versions: Not specified

Complete source record

{
  "id": "d62f57e43c601de8ddc07ddba4af1ee158c63e48f01ec448adc92338f74e2ed2",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2025-65015",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2025-65015",
    "summary": "joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions from 1.3.3 to before 1.3.5 and from 1.4.0 to before 1.4.2, the ExceededSizeError exception messages are embedded with non-decoded JWT token parts and may cause Python logging to record an arbitrarily large, forged JWT payload. In situations where a misconfigured — or entirely absent — production-grade web server sits in front of a Python web application, an attacker may be able to send arbitrarily large bearer tokens in the HTTP request headers. When this occurs, Python logging or diagnostic tools (e.g., Sentry) may end up processing extremely large log messages containing the full JWT header during the joserfc.jwt.decode() operation. The same behavior also appears when validating claims and signature payload sizes, as the library raises joserfc.errors.ExceededSizeError() with the full payload embedded in the exception message. Since the payload is already fully loaded into memory at this stage, the library cannot prevent or reject it. This issue has been patched in versions 1.3.5 and 1.4.2.",
    "evidence": "osv:UBUNTU-CVE-2025-65015",
    "products": [
      {
        "name": {
          "value": "joserfc",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.0.4-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.1.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.2.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.2.2-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "joserfc",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.6.2-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.6.5-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.6.8-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.7.0-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.7.1-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.7.2-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.7.4-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "joserfc",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.2.2-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.4.0-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.4.1-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.4.3-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.5.0-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.6.2-1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "UBUNTU-CVE-2025-65015",
      "aliases": [
        "UBUNTU-CVE-2025-65015"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H"
        },
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "joserfc",
            "purl": "pkg:deb/ubuntu/joserfc?arch=source&distro=questing",
            "ecosystem": "Ubuntu:25.10"
          },
          "versions": [
            "1.0.4-1",
            "1.1.0-1",
            "1.2.0-1",
            "1.2.2-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-65015.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-joserfc",
                "binary_version": "1.2.2-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "joserfc",
            "purl": "pkg:deb/ubuntu/joserfc?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "1.6.2-1",
            "1.6.5-1",
            "1.6.8-1",
            "1.7.0-1",
            "1.7.1-1",
            "1.7.2-1",
            "1.7.4-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-65015.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-joserfc",
                "binary_version": "1.7.4-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "joserfc",
            "purl": "pkg:deb/ubuntu/joserfc?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "1.2.2-1",
            "1.4.0-1",
            "1.4.1-1",
            "1.4.3-1",
            "1.5.0-1",
            "1.6.2-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-65015.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-joserfc",
                "binary_version": "1.6.2-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:58:39.284086602Z",
      "provider": "osv",
      "upstream": [
        "CVE-2025-65015"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2025-65015",
        "https://www.cve.org/CVERecord?id=CVE-2025-65015",
        "https://github.com/authlib/joserfc/security/advisories/GHSA-frfh-8v73-gjg4",
        "https://github.com/authlib/joserfc/commit/63932f169d924caffafa761af2122b82059017f7",
        "https://github.com/authlib/joserfc/commit/673c8743fd0605b0e1de6452be6cba75f44e466b",
        "https://github.com/authlib/joserfc/releases/tag/1.3.5",
        "https://github.com/authlib/joserfc/releases/tag/1.4.2"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2025-65015",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 358939,
  "published_at": "2025-11-18T23:15:00+00:00"
}