HIGH

CVE-2026-102271

CVSS v3

7.4

HIGH

EPSS Score

0.2 %

exploit probability, as of 2026-09-29

CISA KEV

known exploited

Exploitation

—

SSVC status

Description

PyJWT is a Python implementation of JSON Web Token standards. From 2.4.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because asymmetric-key guard relies on textual markers that are absent from DER encoding. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a DER public key as the shared verification key. As a result, PyJWT uses public DER bytes as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens.

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published: 2026-09-28
Last Modified: 2026-09-28

Frequently asked questions

What is CVE-2026-102271?

Is CVE-2026-102271 actively exploited?

Active exploitation of CVE-2026-102271 has not been confirmed. Its EPSS score was 0.2% on 2026-09-29, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-102271?

CVE-2026-102271 has a CVSS v3 base score of 7.4 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

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