What is CVE-2026-102268?

CVE-2026-102268 is a critical-severity vulnerability in Jpadilla Pyjwt, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.1/10. Published 2026-09-28.

How severe is CVE-2026-102268?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Jpadilla Pyjwt

CVE-2026-102268

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.

Published 2026-09-28 · last modified 2026-09-29.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Jpadilla Pyjwt — versions < 2.14.0

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

References

Frequently asked questions

What is CVE-2026-102268?: CVE-2026-102268 is a critical-severity vulnerability in Jpadilla Pyjwt, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.1/10. Published 2026-09-28.
How severe is CVE-2026-102268?: Critical severity. CVSS v3 base score is 9.1 out of 10.