CVE-2026-48990

Description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions 1.3.4 through 1.6.5, joserfc accepts oversized RFC7797 b64=false JWS payloads without applying JWSRegistry.max_payload_length, which can lead to resource exhaustion. The normal JWS compact and flattened JSON paths reject payloads above the configured payload-size limit with ExceededSizeError. The RFC7797 unencoded payload paths do not make the same check. A valid b64=false compact or flattened JSON JWS can therefore deserialize successfully with a payload larger than JWSRegistry.max_payload_length. Applications that accept lower-trust JWS values and rely on joserfc to reject oversized token content during verification have a moderate availability risk. This issue has been fixed in version 1.6.7.

CVSS Metrics

• v3.1•MEDIUM•Score: 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Trends

Current EPSS score: 0.16%• Percentile: 6%

Techniques & Countermeasures

• CWE-400•Uncontrolled Resource Consumption

  The product does not properly control the allocation and maintenance of a limited resource.

• CWE-770•Allocation of Resources Without Limits or Throttling

  The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Affected Systems

• authlib•joserfc

  < 1.6.7

• PyPI•joserfc

  ≥ 1.3.4, < 1.6.7

References (6)

• https://github.com/authlib/joserfc/security/advisories/GHSA-wphv-vfrh-23q5
• https://github.com/authlib/joserfc/releases/tag/1.6.7
• https://nvd.nist.gov/vuln/detail/CVE-2026-48990
• https://github.com/authlib/joserfc
• https://pypi.org/project/joserfc
• https://github.com/advisories/GHSA-wphv-vfrh-23q5