CVE-2026-62995

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. in versions 1.7.1 and prior, joserfc accepts JWTs with trailing padding (==) which are not conforming to the JOSE specifications. This leads to malleability of the JWTs when consumed by joserfc. Depending on this application this might or not be an issue. This could lead to bypass of token revocation or anti-replay protection when implemented as a deny list of tokens or a deny list of token hashes. Note that ECDSA JWS are always malleable because of the malleability of ECDSA signatures (first test case in the code bellow). This makes a scheme which assumes that JWTs are not malleable brittle. However for other signatures (or MAC) schemes it might make sense to assume non malleability of the token. This issue has been fixed in version 1.7.2.

CVSS

No CVSS.

References

Link	Resource
https://github.com/authlib/joserfc/security/advisories/GHSA-5jhw-7jv7-qcqq

Configurations

No configuration.

History

29 Jul 2026, 19:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-29 19:16

Updated : 2026-07-30 19:59

NVD link : CVE-2026-62995

Mitre link : CVE-2026-62995

CVE.ORG link : CVE-2026-62995

JSON object : View

Products Affected

No product.

CWE

CWE-345

Insufficient Verification of Data Authenticity

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