pyjwt — security advisory

{
  "id": "0c4a069573093b0d1a2076715de49a022651855fec777d347aacf89ee1577494",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-48523",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-48523",
    "summary": "PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode() or jwt.decode_complete() are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature verification is performed with the algorithm bound to the PyJWK object instead of the header algorithm. An attacker who controls a registered JWK/JWKS private key can sign with a disallowed algorithm, advertise an allowed algorithm in the JWT header, and still be accepted. The issue affects the documented PyJWKClient.get_signing_key_from_jwt(...) flow. This vulnerability is fixed in 2.13.0.",
    "evidence": "osv:DEBIAN-CVE-2026-48523",
    "products": [
      {
        "name": {
          "value": "pyjwt",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.10.1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.10.1-2+deb13u1",
            "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"
          }
        ]
      },
      {
        "name": {
          "value": "pyjwt",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.13.0-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.10.1-2",
            "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"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2026-48523",
      "aliases": [
        "DEBIAN-CVE-2026-48523"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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=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-2026-48523.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-2026-48523.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-26T11:47:32.634799279Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-48523"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-48523"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-48523",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 450756,
  "published_at": "2026-05-28T16:16:29.28+00:00"
}