# CVE-2024-54150: Algorithm Confusion Vulnerability in cjwt

> Attackers can bypass JWT signature verification by confusing HMAC and asymmetric algorithms, leading to unauthorized access in applications using the cjwt library.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Dec 2024
- **Updated:** 20 Dec 2024
- **Also known as:** GHSA-9h24-7qp5-gp82

## What is CVE-2024-54150?

CVE-2024-54150 is a high-severity vulnerability in xmidt-org cjwt, published on 19 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

cjwt is a C JSON Web Token (JWT) Implementation. Algorithm confusion occurs when a system improperly verifies the type of signature used, allowing attackers to exploit the lack of distinction between signing methods.  If the system doesn't differentiate between an HMAC signed token and an RS/EC/PS signed token during verification, it becomes vulnerable to this kind of attack. For instance, an attacker could craft a token with the alg field set to "HS256" while the server expects an asymmetric algorithm like "RS256". The server might mistakenly use the wrong verification method, such as using a public key as the HMAC secret, leading to unauthorised access. For RSA, the key can be computed from a few signatures. For Elliptic Curve (EC), two potential keys can be recovered from one signature. This can be used to bypass the signature mechanism if an application relies on asymmetrically signed tokens. This issue has been addressed in version 2.3.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2024-54150?


## How do I fix CVE-2024-54150?

No fix has been published for CVE-2024-54150 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-54150 being exploited?

There is no known exploitation of CVE-2024-54150 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-54150 and fix it if it is affected.

What it is: CVE-2024-54150 is a high-severity vulnerability in xmidt-org cjwt, published on 19 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-54150 in the wild and no public exploit code.

Affected product: xmidt-org cjwt. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-54150/ (Markdown: https://insights.sbomify.com/CVE-2024-54150/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-54150
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-54150
- OSV: https://osv.dev/vulnerability/CVE-2024-54150

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-54150/
Summaries are generated and may contain mistakes; the official description above is the record.