CVE-2026-48990

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 3.1

5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

0.2% chance of exploitation in the next 30 days; higher than 5% of CVEs (scores of 2026-10-25)

CWEs

CWE-400, CWE-770

Published

2026-06-17

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Packages (OSV)

References

• https://github.com/authlib/joserfc/releases/tag/1.6.7
• https://github.com/authlib/joserfc/security/advisories/GHSA-wphv-vfrh-23q5
• https://github.com/authlib/joserfc/security/advisories/GHSA-wphv-vfrh-23q5

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