Vulnerability Description
In Puma (RubyGem) before 4.3.2 and before 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Puma | Puma | <= 3.12.3 |
| Ruby-Lang | Ruby | <= 2.3.0 |
| Debian | Debian Linux | 9.0 |
| Fedoraproject | Fedora | 30 |
Related Weaknesses (CWE)
References
- https://github.com/puma/puma/security/advisories/GHSA-84j7-475p-hp8vMitigationThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/05/msg00034.htmlMailing ListThird Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://owasp.org/www-community/attacks/HTTP_Response_SplittingThird Party Advisory
- https://www.ruby-lang.org/en/news/2019/10/01/http-response-splitting-in-webrick-Vendor Advisory
- https://github.com/puma/puma/security/advisories/GHSA-84j7-475p-hp8vMitigationThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/05/msg00034.htmlMailing ListThird Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://owasp.org/www-community/attacks/HTTP_Response_SplittingThird Party Advisory
- https://www.ruby-lang.org/en/news/2019/10/01/http-response-splitting-in-webrick-Vendor Advisory
FAQ
What is CVE-2020-5247?
CVE-2020-5247 is a vulnerability with a CVSS score of 6.5 (MEDIUM). In Puma (RubyGem) before 4.3.2 and before 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...
How severe is CVE-2020-5247?
CVE-2020-5247 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2020-5247?
Check the references section above for vendor advisories and patch information. Affected products include: Puma Puma, Ruby-Lang Ruby, Debian Debian Linux, Fedoraproject Fedora.