Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
None
Attack Vector
Network
0

CVE-2021-32749

Disclosure Date: July 16, 2021 •
CVE-2021-32749 CVSS v3 Base Score: 8.1
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

fail2ban is a daemon to ban hosts that cause multiple authentication errors. In versions 0.9.7 and prior, 0.10.0 through 0.10.6, and 0.11.0 through 0.11.2, there is a vulnerability that leads to possible remote code execution in the mailing action mail-whois. Command mail from mailutils package used in mail actions like mail-whois can execute command if unescaped sequences (\n~) are available in “foreign” input (for instance in whois output). To exploit the vulnerability, an attacker would need to insert malicious characters into the response sent by the whois server, either via a MITM attack or by taking over a whois server. The issue is patched in versions 0.10.7 and 0.11.3. As a workaround, one may avoid the usage of action mail-whois or patch the vulnerability manually.

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CVSS V3 Severity and Metrics
Base Score:
8.1 High
Impact Score:
5.9
Exploitability Score:
2.2
Vector:
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Network
Attack Complexity (AC):
High
Privileges Required (PR):
None
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
fail2ban <= 0.9.7
fail2ban >= 0.10.0, <= 0.10.6
fail2ban >= 0.11.0, <= 0.11.2
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • fail2ban,
  • fedoraproject

Products

  • fail2ban,
  • fedora 34,
  • fedora 35
Technical Analysis