jpadilla PyJWT up to 2.13.x HMACAlgorithm HMACAlgorithm.prepare_key signature verification

CVSS Meta Temp Score
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CTI Interest Score
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7.2$0-$5k0.79-

Summaryinfo

A vulnerability categorized as critical has been discovered in jpadilla PyJWT up to 2.13.x. This affects the function HMACAlgorithm.prepare_key of the component HMACAlgorithm. Such manipulation leads to signature verification. This vulnerability is listed as CVE-2026-102271. The attack may be performed from remote. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in jpadilla PyJWT up to 2.13.x and classified as critical. Affected by this issue is the function HMACAlgorithm.prepare_key of the component HMACAlgorithm. The manipulation with an unknown input leads to a signature verification vulnerability. Using CWE to declare the problem leads to CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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. This issue is fixed in version 2.14.0.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-102271 since 09/28/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 2.14.0 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.4
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Signature verification
CWE: CWE-347 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: PyJWT 2.14.0

Timelineinfo

09/28/2026 Advisory disclosed
09/28/2026 +0 days CVE reserved
09/28/2026 +0 days VulDB entry created
09/28/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-102271 (🔒)
GCVE (CVE): GCVE-0-2026-102271
GCVE (VulDB): GCVE-100-411188

Entryinfo

Created: 09/28/2026 22:53
Changes: 09/28/2026 22:53 (65)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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