CVE-2022-23634

Puma used with Rails may lead to Information Exposure

Workarounds

Upgrade to Rails versions 7.02.2, 6.1.4.6, 6.0.4.6, and 5.2.6.2.

The Rails CVE includes a middleware that can be used instead.

References

• Rails CVE: CVE-2022-23633

For more information

If you have any questions or comments about this advisory:

• Open an issue in puma
• See our security policy

Prior to puma version 5.6.2, puma may not always call close on the response body. Rails, prior to version 7.0.2.2, depended on the response body being closed in order for its CurrentAttributes implementation to work correctly.

From Rails:

Under certain circumstances response bodies will not be closed, for example a bug in a webserver[1] or a bug in a Rack middleware. In the event a response is not notified of a close, ActionDispatch::Executor will not know to reset thread local state for the next request. This can lead to data being leaked to subsequent requests, especially when interacting with ActiveSupport::CurrentAttributes.

The combination of these two behaviors (Puma not closing the body + Rails' Executor implementation) causes information leakage.

CVE-2022-23634 has a CVSS score of 8.0 (High). The vector is network-reachable, no privileges required, and user interaction required. 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 (5.6.2, 4.3.11); upgrading removes the vulnerable code path.

Kodem intelligence

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This problem is fixed in Puma versions 5.6.2 and 4.3.11.

This problem is fixed in Rails versions 7.02.2, 6.1.4.6, 6.0.4.6, and 5.2.6.2.

See:
https://github.com/advisories/GHSA-wh98-p28r-vrc9
for details about the rails vulnerability

Upgrading to a patched Rails or Puma version fixes the vulnerability.

1. What is CVE-2022-23634? CVE-2022-23634 is a high-severity security vulnerability in puma (rubygems), affecting versions >= 5.0.0, < 5.6.2. It is fixed in 5.6.2, 4.3.11.
2. How severe is CVE-2022-23634? CVE-2022-23634 has a CVSS score of 8.0 (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.
3. Which versions of puma are affected by CVE-2022-23634? puma (rubygems) versions >= 5.0.0, < 5.6.2 is affected.
4. Is there a fix for CVE-2022-23634? Yes. CVE-2022-23634 is fixed in 5.6.2, 4.3.11. Upgrade to this version or later.
5. Is CVE-2022-23634 exploitable, and should I be worried? Whether CVE-2022-23634 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
6. What actually determines whether CVE-2022-23634 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.
7. How do I fix CVE-2022-23634?
   • Upgrade puma to 5.6.2 or later
   • Upgrade puma to 4.3.11 or later

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