CVE-2026-102268
PyJWT: Asymmetric-PEM detection bypass: whitespace/line-ending-mutated public keys skip the HS/asymmetric confusion guard
CVSS Score
9.1
EPSS Score
0.0%
EPSS Percentile
0th
PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, is_pem_format in jwt/utils.py is affected because is_pem_format does not recognize every PEM representation accepted by the cryptography loader. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a mutated public-key PEM as raw key bytes. As a result, HMACAlgorithm.prepare_key treats the unrecognized asymmetric public key as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This issue is fixed in version 2.14.0.
| CWE | CWE-347 |
| Vendor | jpadilla |
| Product | pyjwt |
| Published | Sep 28, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
jpadilla / pyjwt
< 2.14.0