CVE-2024-45614

Puma's header normalization allows for client to clobber proxy set headers

Workarounds

Nginx has a underscores_in_headers configuration variable to discard these headers at the proxy level.

Any users that are implicitly trusting the proxy defined headers for security or availability should immediately cease doing so until upgraded to the fixed versions.

Clients could clobber values set by intermediate proxies (such as X-Forwarded-For) by providing a underscore version of the same header (X-Forwarded_For). Any users trusting headers set by their proxy may be affected. Attackers may be able to downgrade connections to HTTP (non-SSL) or redirect responses, which could cause confidentiality leaks if combined with a separate MITM attack.

CVE-2024-45614 has a CVSS score of 5.4 (Medium). The vector is network-reachable, no privileges required, and no user interaction. 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 (5.6.9, 6.4.3); upgrading removes the vulnerable code path.

Kodem intelligence

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v6.4.3/v5.6.9 now discards any headers using underscores if the non-underscore version also exists. Effectively, allowing the proxy defined headers to always win.

1. What is CVE-2024-45614? CVE-2024-45614 is a medium-severity security vulnerability in puma (rubygems), affecting versions < 5.6.9. It is fixed in 5.6.9, 6.4.3.
2. How severe is CVE-2024-45614? CVE-2024-45614 has a CVSS score of 5.4 (Medium). 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-2024-45614? puma (rubygems) versions < 5.6.9 is affected.
4. Is there a fix for CVE-2024-45614? Yes. CVE-2024-45614 is fixed in 5.6.9, 6.4.3. Upgrade to this version or later.
5. Is CVE-2024-45614 exploitable, and should I be worried? Whether CVE-2024-45614 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-2024-45614 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-2024-45614?
   • Upgrade puma to 5.6.9 or later
   • Upgrade puma to 6.4.3 or later

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