CVE-2016-2056

HIGH

Xymon 4.1.x-4.3.x - Authenticated Command Injection via adduser_name Argument

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2016-2056. PoCs published by Metasploit, Markus Krell, bcoles, including Metasploit module exploits/unix/webapp/xymon_useradm_cmd_exec.

AI-analyzed exploit summary This Metasploit module exploits a command injection vulnerability in Xymon's useradm.sh script, allowing authenticated users to execute arbitrary commands via improperly sanitized input passed to the htpasswd command.

Description

xymond in Xymon 4.1.x, 4.2.x, and 4.3.x before 4.3.25 allow remote authenticated users to execute arbitrary commands via shell metacharacters in the adduser_name argument in (1) web/useradm.c or (2) web/chpasswd.c.

Exploits (2)

exploitdb WORKING POC VERIFIED
by Metasploit · rubyremotemultiple
https://www.exploit-db.com/exploits/47114

This Metasploit module exploits a command injection vulnerability in Xymon's useradm.sh script, allowing authenticated users to execute arbitrary commands via improperly sanitized input passed to the htpasswd command.

Classification
Working Poc 100%
Attack Type
Rce
Complexity
Trivial
Reliability
Reliable
Target: Xymon versions before 4.3.25
Auth required
Prerequisites: Valid Xymon credentials · Access to the Xymon web interface
devstral-2 · analyzed Feb 16, 2026 Full analysis →
metasploit WORKING POC EXCELLENT
by Markus Krell, bcoles · rubypocunix
https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/unix/webapp/xymon_useradm_cmd_exec.rb

This Metasploit module exploits a command injection vulnerability in Xymon's useradm.sh script, allowing authenticated users to execute arbitrary commands as the web server user. The exploit leverages improper input validation in the username field during user creation.

Classification
Working Poc 100%
Attack Type
Rce
Complexity
Trivial
Reliability
Reliable
Target: Xymon versions before 4.3.25
Auth required
Prerequisites: Valid Xymon credentials · Access to the Xymon web interface
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (5)

Core 5
Core References
Third Party Advisory, VDB Entry mailing-list x_refsource_bugtraq
http://www.securityfocus.com/archive/1/537522/100/0/threaded
Patch x_refsource_confirm
https://sourceforge.net/p/xymon/code/7892/
Third Party Advisory vendor-advisory x_refsource_debian
http://www.debian.org/security/2016/dsa-3495

Scores

CVSS v3 8.8
EPSS 0.5635
EPSS Percentile 98.2%
Attack Vector NETWORK
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Details

CWE
CWE-77
Status published
Products (33)
debian/debian_linux 8.0
xymon/xymon 4.1.0
xymon/xymon 4.1.1
xymon/xymon 4.1.2 (3 CPE variants)
xymon/xymon 4.2 alfa (3 CPE variants)
xymon/xymon 4.2.0
xymon/xymon 4.2.2 (2 CPE variants)
xymon/xymon 4.2.3 (2 CPE variants)
xymon/xymon 4.3.0 (5 CPE variants)
xymon/xymon 4.3.1
... and 23 more
Published Apr 13, 2016
Tracked Since Feb 18, 2026