CVE-2026-48990CWE-400CWE-770

joserfc: b64=false RFC7797 JWS payloads bypass JWSRegistry payload-size limits during deserialization

Medium · published June 17, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
17.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00265 · 17.4th percentile
Weaknesses
CWE-400 · Uncontrolled Resource Consumption; CWE-770 · Allocation of Resources Without Limits or Throttling
Published
2026-06-17T21:08Z
EPSS history
Timeline
  • 17 JUN 21:08Z
    joserfc: b64=false RFC7797 JWS payloads bypass JWSRegistry payload-size limits during deserialization
    cvelistv5