Summary
jsonwebtoken unrestricted key type could lead to legacy keys usage
Overview
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.
Am I affected?
You are affected if you are using an algorithm and a key type other than the combinations mentioned below
| Key type | algorithm |
|---|---|
| ec | ES256, ES384, ES512 |
| rsa | RS256, RS384, RS512, PS256, PS384, PS512 |
| rsa-pss | PS256, PS384, PS512 |
And for Elliptic Curve algorithms:
alg |
Curve |
|---|---|
| ES256 | prime256v1 |
| ES384 | secp384r1 |
| ES512 | secp521r1 |
How do I fix it?
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.
Will the fix impact my users?
There will be no impact, if you update to version 9.0.0 and you already use a valid secure combination of key type and algorithm. Otherwise, use the allowInvalidAsymmetricKeyTypes option to true in the sign() and verify() functions to continue usage of invalid key type/algorithm combination in 9.0.0 for legacy compatibility.
Impact
The application uses a cryptographic algorithm known to have weaknesses, such as MD5, SHA-1, or DES. Typical impact: compromised confidentiality or integrity of protected data.
CVE-2022-23539 has a CVSS score of 8.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.0.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2022-23539? CVE-2022-23539 is a high-severity use of a broken or risky cryptographic algorithm vulnerability in jsonwebtoken (npm), affecting versions <= 8.5.1. It is fixed in 9.0.0. The application uses a cryptographic algorithm known to have weaknesses, such as MD5, SHA-1, or DES.
- How severe is CVE-2022-23539? CVE-2022-23539 has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of jsonwebtoken are affected by CVE-2022-23539? jsonwebtoken (npm) versions <= 8.5.1 is affected.
- Is there a fix for CVE-2022-23539? Yes. CVE-2022-23539 is fixed in 9.0.0. Upgrade to this version or later.
- Is CVE-2022-23539 exploitable, and should I be worried? Whether CVE-2022-23539 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2022-23539 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2022-23539? Upgrade
jsonwebtokento 9.0.0 or later.