CVE-2020-5249: HTTP Response Splitting (Early Hints) in Puma
Impact 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: Open an issue in puma Email us a project maintainer. Email addresses are listed in our Code of Conduct.
Other sources
Impact 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: Open an issue in puma Email us a project maintainer. Email addresses are listed in our Code of Conduct.
In Puma (RubyGem) before 4.3.3 and 3.12.4, 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. This has been fixed in 4.3.3 and 3.12.4.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
rubygems/pumato a version that resolves this vulnerability.Fixed in 4.3.3 - Upgrade
Upgrade
rubygems/pumato a version that resolves this vulnerability.Fixed in 3.12.4 - Upgrade
Upgrade
pumato a version that resolves this vulnerability.Fixed in 4.3.3 - Upgrade
Upgrade
pumato a version that resolves this vulnerability.Fixed in 3.12.4 - Compensating control
Ensure the Early Hints response header in applications using Puma does not include untrusted/user input (disallow untrusted input in the Early Hints response header).
Event History
Frequently Asked Questions
What is CVE-2020-5249?
CVE-2020-5249 is a vulnerability in Puma (RubyGem) that allows an attacker to inject malicious content by using a carriage return character in the early-hints header.
What is the impact of CVE-2020-5249?
The impact of CVE-2020-5249 is that an attacker can inject additional headers or an entirely new response body.
Which software versions are affected by CVE-2020-5249?
Puma versions before 4.3.3 and 3.12.4 are affected by CVE-2020-5249.
How can I fix CVE-2020-5249?
To fix CVE-2020-5249, upgrade Puma to version 4.3.3 or 3.12.4 depending on your current version.
What is the severity of CVE-2020-5249?
CVE-2020-5249 has a severity rating of 6.5 (medium).