Critical 9.1Published Sep 28, 2026

CVE-2026-102268PyJWT: Asymmetric-PEM detection bypass: whitespace/line-ending-mutated public keys skip the HS/asymmetric confusion guard

Updated under an hour ago (2026-10-19 09:10 UTC)

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It affects jpadilla pyjwt and 1 other product. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.20%, higher than 9% of scored CVEs.

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Every CVE for jpadilla pyjwt

Exploited in the last 30 days

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: 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-347
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.20% (percentile 9)
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Sep 29, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

jpadilla pyjwt jpadilla:pyjwt (from the name)	before 2.14.0	CNA record
pyjwt_project pyjwt pyjwt_project:pyjwt	before 2.14.0	NVD

References

https://github.com/jpadilla/pyjwt/security/advisories/GHSA-ffc3-869f-jxw9x-refsource-confirm, exploit, vendor-advisory
https://github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07x-refsource-misc, patch
https://github.com/jpadilla/pyjwt/releases/tag/2.14.0x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.