Vulnerability Details : CVE-2021-32749
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.
Vulnerability category: Execute code
Exploit prediction scoring system (EPSS) score for CVE-2021-32749
Probability of exploitation activity in the next 30 days: 0.56%
Percentile, the proportion of vulnerabilities that are scored at or less: ~ 75 % EPSS Score History EPSS FAQ
CVSS scores for CVE-2021-32749
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|
|
6.8
|
MEDIUM | AV:N/AC:M/Au:N/C:P/I:P/A:P |
8.6
|
6.4
|
[email protected] |
|
8.1
|
HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
2.2
|
5.9
|
[email protected] |
|
6.1
|
MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N |
1.6
|
4.0
|
[email protected] |
CWE ids for CVE-2021-32749
-
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.Assigned by: [email protected] (Primary)
-
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.Assigned by: [email protected] (Secondary)
References for CVE-2021-32749
-
https://github.com/fail2ban/fail2ban/commit/410a6ce5c80dd981c22752da034f2529b5eee844
Patch;Third Party Advisory
-
https://github.com/fail2ban/fail2ban/security/advisories/GHSA-m985-3f3v-cwmm
Exploit;Patch;Third Party Advisory
-
https://github.com/fail2ban/fail2ban/commit/2ed414ed09b3bb4c478abc9366a1ff22024a33c9
Patch;Third Party Advisory
-
https://lists.fedoraproject.org/archives/list/[email protected]/message/ZRYQ77MTX5WSV33VCJLK4KBKR55QZ7ZA/
Mailing List;Third Party Advisory
-
https://lists.fedoraproject.org/archives/list/[email protected]/message/5WHJK2X2MR2WDYZMCW7COZXJDUSDYMY6/
Mailing List;Third Party Advisory
Products affected by CVE-2021-32749
- cpe:2.3:a:fail2ban:fail2ban:*:*:*:*:*:*:*:*
- cpe:2.3:a:fail2ban:fail2ban:*:*:*:*:*:*:*:*
- cpe:2.3:a:fail2ban:fail2ban:*:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*