CVE-2024-45614: Header normalization allows for client to clobber proxy set headers in Puma
Impact
Clients could clobber values set by intermediate proxies (such as X-Forwarded-For) by providing a underscore version of the same header (X-ForwardedFor). 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.
Patches 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.
Workarounds Nginx has a underscoresinheaders 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.
Other sources
Puma is a Ruby/Rack web server built for parallelism. In affected versions clients could clobber values set by intermediate proxies (such as X-Forwarded-For) by providing a underscore version of the same header (X-ForwardedFor). Any users relying on proxy set variables is affected. 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. Users are advised to upgrade. Nginx has a underscoresinheaders configuration variable to discard these headers at the proxy level as a mitigation. Any users that are implicitly trusting the proxy defined headers for security should immediately cease doing so until upgraded to the fixed versions.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2024-45614?
CVE-2024-45614 has been assessed as a medium-severity vulnerability affecting header values trusted by clients.
How do I fix CVE-2024-45614?
To fix CVE-2024-45614, upgrade to Puma version 6.4.3 or 5.6.9 or patch older versions as recommended.
What software is affected by CVE-2024-45614?
CVE-2024-45614 affects Puma versions between 6.0.0 and 6.4.3, as well as versions up to 5.6.9.
What type of attack does CVE-2024-45614 enable?
CVE-2024-45614 allows attackers to potentially downgrade network connections and manipulate header values.
Who is impacted by CVE-2024-45614?
Users who trust intermediary proxies that set HTTP headers may be affected by CVE-2024-45614.