Cyber Resilience

CVE-2016-2056

RCE in Xymon 4.1.0 … 4.3.9

Public PoCHigh EPSSRCECommand Injection
Published
13 April 2016
Modified
06 May 2026
Patch / advisory
CVSS Score v3 8.8
Click a component to see what it means
Raw vectorCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.55 99th percentile
Risk Priority 80 floored blend · peak EPSS

Summary

CVE-2016-2056 is a high-severity Command Injection (CWE-77) vulnerability in Xymon Xymon. Its CVSS base score is 8.8 (High).

Operationally, ranked in the top 1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

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.

CWE(s)

Related Threats

Likely ATT&CK TechniquesAI

Techniques this vulnerability likely enables, inferred from its description, weakness type, and attributed-actor tradecraft. Confidence is per-technique.

T1190 Exploit Public-Facing Application Initial Accessconfidence: HIGH
Remote authenticated users can inject shell metacharacters to execute arbitrary commands on the Xymon server.
T1059.004 Unix Shell Executionconfidence: HIGH
Shell metacharacters in the adduser_name parameter are passed directly to a Unix shell, enabling command execution.
inferred from description + CWE · MITRE ATT&CK Enterprise v19.0

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CVE-2019-5420Same product: Debian Debian Linux
CVE-2012-1823Same product: Debian Debian Linux
CVE-2025-37948Same product: Debian Debian Linux
CVE-2025-38320Same product: Debian Debian Linux
CVE-2025-38020Same product: Debian Debian Linux
CVE-2021-21311Same product: Debian Debian Linux
CVE-2025-37998Same product: Debian Debian Linux

Affected Assets

xymon
xymon
4.1.0, 4.1.1, 4.1.2, 4.2, 4.2.0
debian
debian linux
8.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.2.3
  • V1.2.5
  • V1.2.8
  • V1.2.9

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require input validation and neutralization that prevent command injection.

DE.CM-09 partial match
prevents

Runtime monitoring of software and data can detect anomalous command execution resulting from injection.

ID.RA-01 partial match
prevents

Identifying recorded vulnerabilities enables remediation of command-injection flaws before exploitation.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Secure coding standards require proper escaping and parameterization of commands, directly eliminating CWE-77.

detects

Security testing in development catches command-injection vulnerabilities before release.

prevents

Secure development life cycle mandates input validation and command construction practices that directly prevent command injection.

prevents

Application security requirements explicitly call for controls against injection flaws including command injection.

prevents

Secure architecture principles reduce the attack surface but do not prescribe the specific neutralization techniques needed.

none

Environment separation limits the blast radius of an exploited command injection but does not prevent the flaw itself.

References