Vulnerability identifier: #VU23008

Vulnerability risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-16254

CWE-ID: CWE-113

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Ruby
Universal components / Libraries / Scripting languages

Vendor: Ruby

Description

The vulnerability allows a remote attacker to perform HTTP response splitting attack.

The vulnerability exists due to insufficient validation of CRLF sequences within the WEBrick in Ruby. A remote attacker can send a specially crafted request to the application and perform a spoofing attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Ruby: 1.6 - 2.6.4

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External links
http://www.ruby-lang.org/en/news/2019/10/01/http-response-splitting-in-webrick-cve-2019-16254/
http://www.ruby-lang.org/ja/news/2019/10/01/ruby-2-4-8-released/
http://www.ruby-lang.org/ja/news/2019/10/01/ruby-2-5-7-released/
http://www.ruby-lang.org/ja/news/2019/10/01/ruby-2-6-5-released/
http://hackerone.com/reports/331984

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.