Vulnerability identifier: #VU23009

Vulnerability risk: High

CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-16255

CWE-ID: CWE-94

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Ruby
Universal components / Libraries / Scripting languages

Vendor: Ruby

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation in lib/shell.rb in Ruby when processing Shell#[] and its alias Shell#test. A remote attacker can send a specially crafted request and execute arbitrary Ruby code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

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/code-injection-shell-test-cve-2019-16255/
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/327512

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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.