Vulnerability identifier: #VU23006

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-2019-15845

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Ruby
Universal components / Libraries / Scripting languages

Vendor: Ruby

Description

The vulnerability allows a remote attacker to bypass certain security restrictions.

The vulnerability exists in Ruby due to insufficient validation of user-supplied files within File.fnmatch and File.fnmatch? functions when processing NUL byte in the filename. A remote attacker can bypass implemented security restrictions and gain unauthorized access to the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Ruby: 1.6 - 2.6.4

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External links
http://hackerone.com/reports/44961
http://www.ruby-lang.org/en/news/2019/10/01/ruby-2-4-8-released/
http://www.ruby-lang.org/en/news/2019/10/01/ruby-2-5-7-released/
http://www.ruby-lang.org/en/news/2019/10/01/ruby-2-6-5-released/
http://www.ruby-lang.org/en/news/2019/10/01/nul-injection-file-fnmatch-cve-2019-15845/

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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.