title: jsonwebtoken unrestricted key type could lead to legacy keys usage
description: Versions `<=8.5.1` of `jsonwebtoken` library could be misconfigured so that legacy, insecure key types are used for signature verification. For example, DSA keys could be used with the RS256 algorithm. You are affected if you are using an algorithm and a key type other than a combination listed in the GitHub Security Advisory as unaffected. This issue has been fixed, please update to version 9.0.0. This version validates for asymmetric key type and algorithm combinations. Please refer to the above mentioned algorithm / key type combinations for the valid secure configuration. After updating to version 9.0.0, if you still intend to continue with signing or verifying tokens using invalid key type/algorithm value combinations, you’ll need to set the `allowInvalidAsymmetricKeyTypes` option  to `true` in the `sign()` and/or `verify()` functions.
problem types: CWE-327: Use of a Broken or Risky Cryptographic Algorithm
affected:
{
vendor: auth0
product: node-jsonwebtoken
versions:
version: <= 8.5.1, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 5.9
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: HIGH
privilegesRequired: LOW
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
version: 3.1
]