MediumFix available

pyjwt — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2026-48522

PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient passes its uri argument directly to urllib.request.urlopen() which uses Python stdlib's default OpenerDirector registering HTTPHandler, HTTPSHandler, FTPHandler, FileHandler, and DataHandler. There is currently no documented option to restrict which schemes PyJWKClient will fetch. If an application's jku URL ingestion path accepts attacker-influenced URLs (e.g., from JWT header, configuration file, OAuth flow parameter), the attacker can cause PyJWKClient to read arbitrary local files via file:// (SSRF on local filesystem), cause PyJWKClient to attempt FTP / data-URI fetches (broader SSRF surface), or forge tokens that PyJWT verifies as valid. The library does not directly return non-HTTP(S) URI contents to the attacker; the chained "plant a JWKS to forge tokens" scenario described in the original report requires additional application-layer flaws (attacker write access to a filesystem path, untrusted jku derivation) that this fix does not address. This vulnerability is fixed in 2.13.0.

Products: pyjwt
Affected versions: 2.10.1-1, 2.10.1-2, 2.10.1-2+deb13u1, 2.10.1-3, 2.10.1-4, 2.11.0-2, 2.12.1-1, 2.13.0-1, 2.14.0-1, 2.15.0-1, 2.15.1-1, 2.6.0-1, 2.6.0-1+deb12u1, 2.7.0-1
Fixed versions: 2.13.0-1
CVEs: CVE-2026-48522
Confirmed fixed CVEs: Not specified
Updated in this feed: 1 Nov 2026, 17:52 UTC · Revision 2

Source evidence

DEBIAN-CVE-2026-48522

core-osv · Original source

Published 28 May 2026, 16:16 UTC

osv:DEBIAN-CVE-2026-48522

pyjwt

Fixed versions: Not specified

pyjwt

Fixed versions: Not specified

pyjwt

Fixed versions: 2.13.0-1

Complete source record

{
  "id": "2b368f3ab520fb83d026c8d53bcb4e1f98b41267529f696d91c09a8bc99e144a",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-48522",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-48522",
    "summary": "PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient passes its uri argument directly to urllib.request.urlopen() which uses Python stdlib's default OpenerDirector registering HTTPHandler, HTTPSHandler, FTPHandler, FileHandler, and DataHandler. There is currently no documented option to restrict which schemes PyJWKClient will fetch. If an application's jku URL ingestion path accepts attacker-influenced URLs (e.g., from JWT header, configuration file, OAuth flow parameter), the attacker can cause PyJWKClient to read arbitrary local files via file:// (SSRF on local filesystem), cause PyJWKClient to attempt FTP / data-URI fetches (broader SSRF surface), or forge tokens that PyJWT verifies as valid. The library does not directly return non-HTTP(S) URI contents to the attacker; the chained \"plant a JWKS to forge tokens\" scenario described in the original report requires additional application-layer flaws (attacker write access to a filesystem path, untrusted jku derivation) that this fix does not address. This vulnerability is fixed in 2.13.0.",
    "evidence": "osv:DEBIAN-CVE-2026-48522",
    "products": [
      {
        "name": {
          "value": "pyjwt",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.10.1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.10.1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.10.1-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.10.1-4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.11.0-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.12.1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.13.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.14.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.15.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.15.1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.6.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.6.0-1+deb12u1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.7.0-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "pyjwt",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.10.1-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-2+deb13u1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-3",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-4",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.11.0-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.12.1-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.13.0-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.14.0-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.15.0-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.15.1-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "pyjwt",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.13.0-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.10.1-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "2.10.1-3",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "2.10.1-4",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "2.11.0-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "2.12.1-1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2026-48522",
      "aliases": [
        "DEBIAN-CVE-2026-48522"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "pyjwt",
            "purl": "pkg:deb/debian/pyjwt?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "2.10.1-1",
            "2.10.1-2",
            "2.10.1-3",
            "2.10.1-4",
            "2.11.0-2",
            "2.12.1-1",
            "2.13.0-1",
            "2.14.0-1",
            "2.15.0-1",
            "2.15.1-1",
            "2.6.0-1",
            "2.6.0-1+deb12u1",
            "2.7.0-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48522.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "pyjwt",
            "purl": "pkg:deb/debian/pyjwt?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "versions": [
            "2.10.1-2",
            "2.10.1-2+deb13u1",
            "2.10.1-3",
            "2.10.1-4",
            "2.11.0-2",
            "2.12.1-1",
            "2.13.0-1",
            "2.14.0-1",
            "2.15.0-1",
            "2.15.1-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48522.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.13.0-1"
                }
              ]
            }
          ],
          "package": {
            "name": "pyjwt",
            "purl": "pkg:deb/debian/pyjwt?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "2.10.1-2",
            "2.10.1-3",
            "2.10.1-4",
            "2.11.0-2",
            "2.12.1-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48522.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-27T09:47:43.408072859Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-48522"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-48522"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-48522",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 461397,
  "published_at": "2026-05-28T16:16:29.15+00:00"
}