# CVE-2023-51774: json-jwt allows bypass of identity checks via a sign/encryption confusion attack

> Attackers can bypass identity checks in the Ruby json-jwt gem by exploiting a sign/encryption confusion vulnerability in JWE handling.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Dec 2023
- **Updated:** 26 Aug 2024
- **Also known as:** GHSA-c8v6-786g-vjx6, UBUNTU-CVE-2023-51774

## What is CVE-2023-51774?

CVE-2023-51774 is a high-severity authentication bypass vulnerability in n/a, published on 25 Dec 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The json-jwt (aka JSON::JWT) gem 1.16.3 for Ruby sometimes allows bypass of identity checks via a sign/encryption confusion attack. For example, JWE can sometimes be used to bypass JSON::JWT.decode.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2023-51774?

4 open source packages ship an affected version, including json-jwt. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `json-jwt` | RubyGems | All versions | 1.15.3.1 |
| `json-jwt` | RubyGems | All versions | 1.15.3.1 |
| `json-jwt` | RubyGems | From 1.16.0 | 1.16.6 |
| `json-jwt` | RubyGems | From 1.16.0 | 1.16.6 |

Products: Json-Jwt Project Json-Jwt.

## How do I fix CVE-2023-51774?

Upgrade json-jwt to a fixed version for your release line: 1.15.3.1 or 1.16.6.

## Is CVE-2023-51774 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-51774 exists.

## Other vulnerabilities in n/a

- [CVE-2018-1000539](https://insights.sbomify.com/CVE-2018-1000539/): Json-jwt did not verify the cryptographic signature for data (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-51774 and fix it if it is affected.

What it is: CVE-2023-51774 is a high-severity authentication bypass vulnerability in n/a, published on 25 Dec 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-51774 exists.

Affected packages and fixed versions:
- json-jwt (RubyGems): affected all versions; fixed in 1.15.3.1
- json-jwt (RubyGems): affected all versions; fixed in 1.15.3.1
- json-jwt (RubyGems): affected from 1.16.0; fixed in 1.16.6
- json-jwt (RubyGems): affected from 1.16.0; fixed in 1.16.6

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-2023-51774/ (Markdown: https://insights.sbomify.com/CVE-2023-51774/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-51774
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-51774
- OSV: https://osv.dev/vulnerability/CVE-2023-51774

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-51774/
Summaries are generated and may contain mistakes; the official description above is the record.