CVE-2026-102268: critical vulnerability in jpadilla pyjwt
PyJWT: Asymmetric-PEM detection bypass: whitespace/line-ending-mutated public keys skip the HS/asymmetric confusion guard
Published · Updated
48Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 9.1epss 0.2%
from disclosure to weapon4 days
Published on NVDSep 28
1st PoC+4d
exploitation probability
0.2%top 92% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected products
jpadilla · pyjwtpublic PoCs found — 1
githubgithub.com/covepseng/cve-2026-102268-poc★ 0⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
Related CVEs — jpadilla pyjwt
In the same product, most dangerous first.
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