🚨 Your current dependencies have known security vulnerabilities 🚨
This dependency update fixes known security vulnerabilities. Please see the details below and assess their impact carefully. We recommend to merge and deploy this as soon as possible!
Here is everything you need to know about this update. Please take a good look at what changed and the test results before merging this pull request.
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.
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 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.
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 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.
Prior to versions 6.4.2 and 5.6.8, puma exhibited dangerous behavior when parsing chunked transfer encoding bodies.
Fixed versions limit the size of chunk extensions. Without this limit, an attacker could cause unbounded resource (CPU, network bandwidth) consumption.
Patches
The vulnerability has been fixed in 6.4.2 and 5.6.8.
Prior to versions 6.4.2 and 5.6.8, puma exhibited dangerous behavior when parsing chunked transfer encoding bodies.
Fixed versions limit the size of chunk extensions. Without this limit, an attacker could cause unbounded resource (CPU, network bandwidth) consumption.
Patches
The vulnerability has been fixed in 6.4.2 and 5.6.8.
Prior to version 6.3.1, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies and zero-length Content-Length headers in a way that allowed HTTP request smuggling.
The following vulnerabilities are addressed by this advisory:
Incorrect parsing of trailing fields in chunked transfer encoding bodies
Parsing of blank/zero-length Content-Length headers
Patches
The vulnerability has been fixed in 6.3.1 and 5.6.7.
Prior to version 6.3.1, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies and zero-length Content-Length headers in a way that allowed HTTP request smuggling.
The following vulnerabilities are addressed by this advisory:
Incorrect parsing of trailing fields in chunked transfer encoding bodies
Parsing of blank/zero-length Content-Length headers
Patches
The vulnerability has been fixed in 6.3.1 and 5.6.7.
When using Puma behind a proxy that does not properly validate that the incoming HTTP request matches the RFC7230 standard, Puma and the frontend proxy may disagree on where a request starts and ends. This would allow requests to be smuggled via the front-end proxy to Puma.
The following vulnerabilities are addressed by this advisory:
Lenient parsing of Transfer-Encoding headers, when unsupported encodings should be rejected and the final encoding must be chunked.
Lenient parsing of malformed Content-Length headers and chunk sizes, when only digits and hex digits should be allowed.
Lenient parsing of duplicate Content-Length headers, when they should be rejected.
Lenient parsing of the ending of chunked segments, when they should end with \r\n.
The vulnerability has been fixed in 5.6.4 and 4.3.12. When deploying a proxy in front of Puma, turning on any and all functionality to make sure that the request matches the RFC7230 standard.
These proxy servers are known to have "good" behavior re: this standard and upgrading Puma may not be necessary. Users are encouraged to validate for themselves.
When using Puma behind a proxy that does not properly validate that the incoming HTTP request matches the RFC7230 standard, Puma and the frontend proxy may disagree on where a request starts and ends. This would allow requests to be smuggled via the front-end proxy to Puma.
The following vulnerabilities are addressed by this advisory:
Lenient parsing of Transfer-Encoding headers, when unsupported encodings should be rejected and the final encoding must be chunked.
Lenient parsing of malformed Content-Length headers and chunk sizes, when only digits and hex digits should be allowed.
Lenient parsing of duplicate Content-Length headers, when they should be rejected.
Lenient parsing of the ending of chunked segments, when they should end with \r\n.
The vulnerability has been fixed in 5.6.4 and 4.3.12. When deploying a proxy in front of Puma, turning on any and all functionality to make sure that the request matches the RFC7230 standard.
These proxy servers are known to have "good" behavior re: this standard and upgrading Puma may not be necessary. Users are encouraged to validate for themselves.
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.
Patches
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.
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.
Patches
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.
Prior to puma version 5.5.0, using puma with a proxy which forwards LF characters as line endings could allow HTTP request smuggling. A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client.
This behavior (forwarding LF characters as line endings) is very uncommon amongst proxy servers, so we have graded the impact here as "low". Puma is only aware of a single proxy server which has this behavior.
If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client.
Patches
This vulnerability was patched in Puma 5.5.1 and 4.3.9.
Workarounds
This vulnerability only affects Puma installations without any proxy in front.
Use a proxy which does not forward LF characters as line endings.
Proxies which do not forward LF characters as line endings:
Prior to puma version 5.5.0, using puma with a proxy which forwards LF characters as line endings could allow HTTP request smuggling. A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client.
This behavior (forwarding LF characters as line endings) is very uncommon amongst proxy servers, so we have graded the impact here as "low". Puma is only aware of a single proxy server which has this behavior.
If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client.
Patches
This vulnerability was patched in Puma 5.5.1 and 4.3.9.
Workarounds
This vulnerability only affects Puma installations without any proxy in front.
Use a proxy which does not forward LF characters as line endings.
Proxies which do not forward LF characters as line endings:
The fix for CVE-2019-16770 was incomplete. The original fix only protected existing connections that had already been accepted from having their requests starved by greedy persistent-connections saturating all threads in the same process. However, new connections may still be starved by greedy persistent-connections saturating all threads in all processes in the cluster.
A puma server which received more concurrent keep-alive connections than the server had threads in its threadpool would service only a subset of connections, denying service to the unserved connections.
Patches
This problem has been fixed in puma 4.3.8 and 5.3.1.
Workarounds
Setting queue_requests false also fixes the issue. This is not advised when using puma without a reverse proxy, such as nginx or apache, because you will open yourself to slow client attacks (e.g. slowloris).
The fix for CVE-2019-16770 was incomplete. The original fix only protected existing connections that had already been accepted from having their requests starved by greedy persistent-connections saturating all threads in the same process. However, new connections may still be starved by greedy persistent-connections saturating all threads in all processes in the cluster.
A puma server which received more concurrent keep-alive connections than the server had threads in its threadpool would service only a subset of connections, denying service to the unserved connections.
Patches
This problem has been fixed in puma 4.3.8 and 5.3.1.
Workarounds
Setting queue_requests false also fixes the issue. This is not advised when using puma without a reverse proxy, such as nginx or apache, because you will open yourself to slow client attacks (e.g. slowloris).
This is a similar but different vulnerability to the one patched in 3.12.5 and 4.3.4.
A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client.
If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client.
Patches
The problem has been fixed in Puma 3.12.6 and Puma 4.3.5.
For more information
If you have any questions or comments about this advisory:
If an application using Puma allows untrusted input in an early-hints header, an attacker can use a carriage return character to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as HTTP Response Splitting.
While not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS).
This is related to CVE-2020-5247, which fixed this vulnerability but only for regular responses.
Patches
This has been fixed in 4.3.3 and 3.12.4.
Workarounds
Users can not allow untrusted/user input in the Early Hints response header.
For more information
If you have any questions or comments about this advisory:
In Puma (RubyGem) before 4.3.2 and 3.12.3, if an application using Puma allows untrusted input in a response header, an attacker can use newline characters (i.e. CR, LF or/r, /n) to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as HTTP Response Splitting.
While not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS).
This is related to CVE-2019-16254, which fixed this vulnerability for the WEBrick Ruby web server.
This has been fixed in versions 4.3.2 and 3.12.3 by checking all headers for line endings and rejecting headers with those characters.
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🚨 Your current dependencies have known security vulnerabilities 🚨
This dependency update fixes known security vulnerabilities. Please see the details below and assess their impact carefully. We recommend to merge and deploy this as soon as possible!
Here is everything you need to know about this update. Please take a good look at what changed and the test results before merging this pull request.
What changed?
✳️ puma (4.3.1 → 6.4.3) · Repo · Changelog
Security Advisories 🚨
🚨 Puma's header normalization allows for client to clobber proxy set headers
🚨 Puma's header normalization allows for client to clobber proxy set headers
🚨 Puma HTTP Request/Response Smuggling vulnerability
🚨 Puma HTTP Request/Response Smuggling vulnerability
🚨 Puma HTTP Request/Response Smuggling vulnerability
🚨 Puma HTTP Request/Response Smuggling vulnerability
🚨 Puma vulnerable to HTTP Request Smuggling
🚨 Puma vulnerable to HTTP Request Smuggling
🚨 Puma used with Rails may lead to Information Exposure
🚨 Puma used with Rails may lead to Information Exposure
🚨 Puma with proxy which forwards LF characters as line endings could allow HTTP request smuggling
🚨 Puma with proxy which forwards LF characters as line endings could allow HTTP request smuggling
🚨 Puma's Keepalive Connections Causing Denial Of Service
🚨 Puma's Keepalive Connections Causing Denial Of Service
🚨 HTTP Smuggling via Transfer-Encoding Header in Puma
🚨 HTTP Smuggling via Transfer-Encoding Header in Puma
🚨 HTTP Response Splitting (Early Hints) in Puma
🚨 HTTP Response Splitting in Puma
Release Notes
Too many releases to show here. View the full release notes.
Commits
See the full diff on Github. The new version differs by more commits than we can show here.
↗️ nio4r (indirect, 2.5.2 → 2.7.3) · Repo · Changelog
Release Notes
2.7.2 (from changelog)
2.7.1
2.7.0
2.5.4 (from changelog)
2.5.3 (from changelog)
Does any of this look wrong? Please let us know.
Commits
See the full diff on Github. The new version differs by more commits than we can show here.
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