Multiple vulnerabilities in Ruby cgi gem

Published: 2021-11-25

Risk	High
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2021-41816 CVE-2021-41819
CWE-ID	CWE-119 CWE-451
Exploitation vector	Network
Public exploit	N/A
Vulnerable software Subscribe	cgi Web applications / Modules and components for CMS
Vendor	Ruby

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Buffer overflow

EUVDB-ID: #VU58364

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-41816

CWE-ID: CWE-119 - Improper Restriction of Operations within the Bounds of a Memory Buffer

Exploit availability: No

Description

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

The vulnerability exists due to a boundary error in CGI.escape_html. A remote attacker can trigger memory corruption and execute arbitrary 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

cgi: 0.1.0 - 0.3.0

CPE2.3

cpe:2.3:a:ruby:cgi:0.1.0:*:*:*:*:*:*:*
Full software list in CPE2.3 format available after registration.

External links

http://www.ruby-lang.org/en/news/2021/11/24/buffer-overrun-in-cgi-escape_html-cve-2021-41816/

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.

2) Spoofing attack

EUVDB-ID: #VU58365

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-2021-41819

CWE-ID: CWE-451 - User Interface (UI) Misrepresentation of Critical Information (Clickjacking, spoofing)