Path traversal in Rubygem Rack

1) Path traversal

EUVDB-ID: #VU67622

Risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-8161

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform directory traversal attacks.

The vulnerability exists due to input validation error when processing directory traversal sequences in Rack::Directory app. A remote attacker can send a specially crafted request and read arbitrary files on the system.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Rack: 2.1.0 - 2.1.2

External links

http://groups.google.com/g/rubyonrails-security/c/IOO1vNZTzPA
http://hackerone.com/reports/434404
http://lists.debian.org/debian-lts-announce/2020/07/msg00006.html
http://usn.ubuntu.com/4561-1/

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.