CVE-2016-2056

HIGHNVD 8.88.9▲
EchelonGraph scoreHIGH confidence

Score elevated to 8.9 because EPSS predicts 55% probability of exploitation within the next 30 days (top 1.1% of all CVEs). NVD baseline CVSS 8.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Weaponized
8.9EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 55%
  • Public exploit code is available (Metasploit, Exploit-DB (verified), epss top5pct, epss high, public exploit)
CISA-KEV: Not listedEPSS PROB: 55%CVSS: 8.8Exploit: Metasploit · Exploit-DB (verified) · epss top5pct · epss high · public exploitExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
8.8
EG Score
8.9(high)
EG Risk
71(Track)
EG Risk 71/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity89% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
55%
EPSS %ILE
99%
KEV
Not listed

Published

April 13, 2016

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated May 22, 2026
No patch confirmed yet.
generic

Xymon Systems and Network Monitor / Code / Commit [r7892]

https://sourceforge.net/p/xymon/code/7892/
generic
http://www.securityfocus.com/archive/1/537522/100/0/threaded
generic

[SECURITY] [DSA 3495-1] xymon security update

http://www.debian.org/security/2016/dsa-3495
generic

Packet Storm

http://packetstormsecurity.com/files/153620/Xymon-useradm-Command-Execution.html

Affected Packages

(6 across 6 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
xymon—4.3.25-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
xymon—4.3.25-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
xymon—4.3.25-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
xymon—4.3.25-1—
Debian:7(1)
PackageVulnerable rangeFixed inDependents
xymon4.3.0~beta2.dfsg-9.14.3.0~beta2.dfsg-9.1+deb7u1—
Debian:8(1)
PackageVulnerable rangeFixed inDependents
xymon4.3.17-64.3.17-6+deb8u1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 21× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-19 16:59 UTCEPSS rescore
  2. 2026-08-18 13:43 UTCEPSS rescore
  3. 2026-08-17 13:42 UTCEPSS rescore
  4. 2026-08-16 14:51 UTCEPSS rescore
  5. 2026-08-16 02:09 UTCEPSS rescore
  6. 2026-08-15 01:25 UTCEPSS rescore
  7. 2026-08-14 12:54 UTCOSV refresh
  8. 2026-08-12 13:46 UTCEPSS rescore
  9. 2026-08-11 13:36 UTCEPSS rescore
  10. 2026-08-08 16:32 UTCEPSS rescore
  11. 2026-08-06 13:42 UTCEPSS rescore
  12. 2026-08-04 15:04 UTCEPSS rescore
  13. 2026-08-04 10:32 UTCEPSS rescore
  14. 2026-07-30 16:23 UTCEPSS rescore
  15. 2026-07-30 01:26 UTCEPSS rescore
  16. 2026-07-30 01:24 UTCOSV refresh
  17. 2026-07-28 15:31 UTCEPSS rescore
  18. 2026-07-26 14:50 UTCEPSS rescore
  19. 2026-07-25 14:13 UTCEPSS rescore
  20. 2026-07-23 14:14 UTCEPSS rescore
  21. 2026-07-23 01:22 UTCEG score recompute▲ 0.10
  22. 2026-07-22 22:01 UTCEG score recompute
  23. 2026-07-22 14:04 UTCEPSS rescore
  24. 2026-07-21 15:21 UTCEPSS rescore
  25. 2026-07-21 15:21 UTCEPSS rescore
Show 73 more
  1. 2026-07-20 17:03 UTCEPSS rescore
  2. 2026-07-19 02:26 UTCEPSS rescore
  3. 2026-07-19 02:26 UTCEPSS rescore
  4. 2026-07-18 10:00 UTCEPSS rescore
  5. 2026-07-18 10:00 UTCEPSS rescore
  6. 2026-07-16 16:59 UTCEPSS rescore
  7. 2026-07-16 16:59 UTCEPSS rescore
  8. 2026-07-15 16:54 UTCEPSS rescore
  9. 2026-07-15 16:54 UTCEPSS rescore
  10. 2026-07-15 01:56 UTCEPSS rescore
  11. 2026-07-15 01:56 UTCEPSS rescore
  12. 2026-07-13 22:26 UTCEPSS rescore
  13. 2026-07-13 06:09 UTCEPSS rescore
  14. 2026-07-12 10:38 UTCOSV refresh
  15. 2026-07-12 05:43 UTCEPSS rescore
  16. 2026-07-12 05:43 UTCEPSS rescore
  17. 2026-07-11 08:23 UTCEPSS rescore
  18. 2026-07-09 19:05 UTCEPSS rescore
  19. 2026-07-06 16:24 UTCEPSS rescore
  20. 2026-07-06 16:24 UTCEPSS rescore
  21. 2026-07-05 02:27 UTCEPSS rescore
  22. 2026-07-01 15:02 UTCEPSS rescore
  23. 2026-06-28 14:04 UTCEPSS rescore
  24. 2026-06-28 04:53 UTCEPSS rescore
  25. 2026-06-27 03:05 UTCEPSS rescore
  26. 2026-06-27 03:05 UTCEPSS rescore
  27. 2026-06-25 13:47 UTCEPSS rescore
  28. 2026-06-25 13:47 UTCEPSS rescore
  29. 2026-06-24 14:02 UTCEPSS rescore
  30. 2026-06-24 14:02 UTCEPSS rescore
  31. 2026-06-23 21:30 UTCEPSS rescore
  32. 2026-06-23 16:20 UTCOSV refresh
  33. 2026-06-21 01:57 UTCEPSS rescore
  34. 2026-06-21 01:57 UTCEPSS rescore
  35. 2026-06-17 17:50 UTCEPSS rescore
  36. 2026-06-17 17:50 UTCEPSS rescore
  37. 2026-06-16 17:50 UTCEPSS rescore
  38. 2026-06-16 17:50 UTCEPSS rescore
  39. 2026-06-15 17:45 UTCEPSS rescore
  40. 2026-06-14 23:14 UTCEPSS rescore
  41. 2026-06-12 23:09 UTCEPSS rescore
  42. 2026-06-12 23:09 UTCEPSS rescore
  43. 2026-06-10 22:15 UTCEPSS rescore
  44. 2026-06-06 21:29 UTCOSV refresh
  45. 2026-06-05 22:44 UTCEPSS rescore
  46. 2026-06-05 06:08 UTCEPSS rescore
  47. 2026-06-05 06:08 UTCEPSS rescore
  48. 2026-06-04 13:10 UTCEPSS rescore
  49. 2026-06-04 13:10 UTCEPSS rescore
  50. 2026-06-02 20:10 UTCEPSS rescore
  51. 2026-06-01 13:49 UTCEPSS rescore
  52. 2026-06-01 13:49 UTCEPSS rescore
  53. 2026-05-31 00:14 UTCEPSS rescore
  54. 2026-05-29 13:41 UTCEPSS rescore
  55. 2026-05-28 13:42 UTCEPSS rescore
  56. 2026-05-28 13:42 UTCEPSS rescore
  57. 2026-05-27 13:38 UTCEPSS rescore
  58. 2026-05-27 13:38 UTCEPSS rescore
  59. 2026-05-26 07:16 UTCEPSS rescore
  60. 2026-05-24 16:43 UTCEPSS rescore
  61. 2026-05-22 21:15 UTCEPSS rescore
  62. 2026-05-22 21:15 UTCEPSS rescore
  63. 2026-05-22 20:50 UTCEG score recompute
  64. 2026-05-22 20:50 UTCGHSA enrichment
  65. 2026-05-22 14:43 UTCOSV refresh
  66. 2026-05-20 22:37 UTCEPSS rescore
  67. 2026-05-20 22:37 UTCEPSS rescore
  68. 2026-05-20 22:37 UTCEPSS rescore
  69. 2026-05-20 11:21 UTCEPSS rescore
  70. 2026-05-20 11:21 UTCEPSS rescore
  71. 2026-05-20 11:21 UTCEPSS rescore
  72. 2026-05-18 21:30 UTCEPSS rescore
  73. 2026-05-18 21:30 UTCEPSS rescore

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 Metasploit module) (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-47114✓ verified
    First seen Jul 12, 2019

    Xymon 4.3.25 - useradm Command Execution (Metasploit)

    Open source ↗
  • Metasploitexploit/unix/webapp/xymon_useradm_cmd_exec✓ verified
    First seen Feb 14, 2016

    Xymon useradm Command Execution

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2016-2056?
CVE-2016-2056 is a high vulnerability published on April 13, 2016. 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.
When was CVE-2016-2056 disclosed?
CVE-2016-2056 was first published in the National Vulnerability Database on April 13, 2016, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-2056 actively exploited?
CVE-2016-2056 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 55% probability of exploitation in the next 30 days, which ranks it in the top 1.1% of all scored CVEs.
What is the CVSS score of CVE-2016-2056?
CVE-2016-2056 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.9.
How do I remediate CVE-2016-2056?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-2056, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2016-2056

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