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    CVE-2026-102266

    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.

    Published:Sep 28, 2026
    Last Modified:Oct 7, 2026
    EPS:Sep 28, 2026
    EPSS Score:0.00175
    CVSS Score:7.4

    Affected Products

    Vendor
    Jpadilla
    Product
    Pyjwt
    Vendor
    Pyjwt Project
    Product
    Pyjwt

    Exploits

    https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3rhttps://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-463 Padding Oracle Crypto Attack
    CAPEC-475 Signature Spoofing by Improper Validation

    Related CVEs

    CVE-2026-103001 (CVSS 6.5) — PyJWT is a Python implementation of JSON Web Token standards. From 2.11.0 through 2.13.0, PyJWT's PyJWT._merge…
    CVE-2026-102265 (CVSS 5.3) — PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWS._load in jwt/api…
    CVE-2026-102275 (CVSS 6.5) — PyJWT is a Python implementation of JSON Web Token standards. From 2.1.0 until 2.15.0, PyJWT OKPAlgorithm.from…
    CVE-2026-102274 (CVSS 5.9) — PyJWT is a Python implementation of JSON Web Token standards. From 2.9.0 until 2.14.0, PyJWKSet does not catch…
    CVE-2026-102273 (CVSS 7.4) — PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWT HMACAlgorithm.pr…
    CVE-2026-102272 (CVSS 7.4) — PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_…
    CVE-2026-102271 (CVSS 7.4) — PyJWT is a Python implementation of JSON Web Token standards. From 2.4.0 until 2.14.0, PyJWT HMACAlgorithm.pre…
    CVE-2026-102270 (CVSS 4.4) — PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT is_pem_format is affected…
    CVE-2026-102269 (CVSS 4.8) — PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT signature segment is affe…
    CVE-2026-102268 (CVSS 9.1) — PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, is_pem_format in jwt/utils.py i…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High