How severe is CVE-2022-23540?

CVE-2022-23540 has a CVSS score of 6.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2022-23540?

CVE-2022-23540 affects the following packages: jsonwebtoken (npm). Ecosystems affected: npm.

How do I fix CVE-2022-23540?

Update jsonwebtoken to 9.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-23540 is resolved across your whole dependency graph.

How do I detect CVE-2022-23540 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsonwebtoken. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2022-23540 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2022-23540?

O3 pinpoints whether CVE-2022-23540 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2022-23540 actively exploited in the wild?

No public exploit code has been indexed for CVE-2022-23540 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2022-23540?

CVE-2022-23540 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 41th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2022-23540 published, and has it been updated?

CVE-2022-23540 was published on December 22, 2022 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

CVE-2022-23540

MEDIUM

jsonwebtoken vulnerable to signature validation bypass due to insecure default algorithm in jwt.verify()

Also known asGHSA-qwph-4952-7xr6

Published

Dec 22, 2022

Updated

Apr 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk41th percentile+0.51%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

📦jsonwebtoken

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

In versions <=8.5.1 of jsonwebtoken library, lack of algorithm definition in the jwt.verify() function can lead to signature validation bypass due to defaulting to the none algorithm for signature verification. Users are affected if you do not specify algorithms in the jwt.verify() function. This issue has been fixed, please update to version 9.0.0 which removes the default support for the none algorithm in the jwt.verify() method. There will be no impact, if you update to version 9.0.0 and you don’t need to allow for the none algorithm. If you need 'none' algorithm, you have to explicitly specify that in jwt.verify() options.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`jsonwebtoken`	all versions	9.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsonwebtoken. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update jsonwebtoken to 9.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-23540 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2022-23540 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2022-23540. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

In versions `<=8.5.1` of `jsonwebtoken` library, lack of algorithm definition in the `jwt.verify()` function can lead to signature validation bypass due to defaulting to the `none` algorithm for signature verification. Users are affected if you do not specify algorithms in the `jwt.verify()` function. This issue has been fixed, please update to version 9.0.0 which removes the default support for the none algorithm in the `jwt.verify()` method. There will be no impact, if you update to version 9.0.0 and you don’t need to allow for the `none` algorithm. If you need 'none' algorithm, you have to

O3 Security · Impact-Aware SCA

Is CVE-2022-23540 in your dependencies?

O3 detects CVE-2022-23540 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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