CVE-2026-120459

    Dashboard / Vulnerabilities / CVE-2026-120459

    CVE-2026-120459

    Published: 2 Nov 2026Last Modified: 4 Nov 2026

    Summary: python-jose through 3.5.0 Authentication Bypass via Empty HMAC Key

    Details: python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge JWTs because HMACKey and CryptographyHMACKey accept zero-length HMAC secrets. When an application's HS256/HS384/HS512 verification key resolves to empty, such as an oct JWK with empty k, attackers can forge tokens with arbitrary claims that jwt.decode accepts.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/120xxx/CVE-2026-120459.json, https://nvd.nist.gov/vuln/detail/CVE-2026-120459, https://www.vulncheck.com/advisories/python-jose-through-3.5.0-authentication-bypass-via-empty-hmac-key, https://github.com/mpdavis/python-jose/issues/398, https://github.com/mpdavis/python-jose, https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/cryptography_backend.py, https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/native.py

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    3.5.0

    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
    CVE-2026-120459 | CVE-DB