jpadilla PyJWT up to 2.13.0 PyJWK verification path HMACAlgorithm.from_jwk improper authentication

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.2$0-$5k0.60

Summaryinfo

A vulnerability was found in jpadilla PyJWT up to 2.13.0. It has been declared as critical. This vulnerability affects the function HMACAlgorithm.from_jwk of the component PyJWK verification path. Executing a manipulation of the argument k can lead to improper authentication. This vulnerability is tracked as CVE-2026-102266. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in jpadilla PyJWT up to 2.13.0. It has been declared as critical. This vulnerability affects the function HMACAlgorithm.from_jwk of the component PyJWK verification path. The manipulation of the argument k with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-102266 since 09/28/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful 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: Improper authentication
CWE: CWE-287
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-2026-102266 (🔒)
GCVE (CVE): GCVE-0-2026-102266
GCVE (VulDB): GCVE-100-411172

Entryinfo

Created: 09/28/2026 22:37
Changes: 09/28/2026 22:37 (66)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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