CVE-2016-9566

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-14. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Weaponized
7.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 5%CVSS: 7.8Exploit: NoneExposed: 0

A fix is available — apply it.

base/logging.c in Nagios Core before 4.2.4 allows local users with access to an account in the nagios group to gain root privileges via a symlink attack on the log file. NOTE: this can be leveraged by remote attackers using CVE-2016-9565.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
66(Track)
EG Risk 66/100SSVC: 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
Severity78% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
91.1%
KEV
Not listed

Published

December 15, 2016

Last Modified

May 6, 2026

References (36)

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntunagios3-doc (3.5.1-1ubuntu1.1) @ trusty2026-05-22ubuntu
redhatnagios-0:3.5.1-9.el62017-02-07redhat
redhatnagios-0:3.5.1-9.el72017-02-07redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

All Vendor Advisories

(7)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 12× in last 7d / 42× 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.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-07-24 14:13 UTCEPSS rescore
  2. 2026-07-23 14:15 UTCEPSS rescore
  3. 2026-07-23 01:24 UTCEG score recompute
  4. 2026-07-22 22:04 UTCEG score recompute
  5. 2026-07-22 14:04 UTCEPSS rescore
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  24. 2026-07-12 05:22 UTCOSV refresh
  25. 2026-07-11 08:24 UTCEPSS rescore
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  1. 2026-07-09 19:06 UTCEPSS rescore
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  19. 2026-06-23 21:30 UTCEPSS rescore
  20. 2026-06-23 11:30 UTCOSV refresh
  21. 2026-06-21 14:54 UTCEPSS rescore
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  23. 2026-06-21 01:57 UTCEPSS rescore
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  25. 2026-06-19 19:23 UTCEPSS rescore
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  27. 2026-06-18 17:50 UTCEPSS rescore
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  37. 2026-06-12 23:09 UTCEPSS rescore
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  39. 2026-06-08 14:14 UTCEPSS rescore
  40. 2026-06-07 15:22 UTCEPSS rescore
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  42. 2026-06-06 13:45 UTCEPSS rescore
  43. 2026-06-06 13:45 UTCEPSS rescore
  44. 2026-06-06 13:17 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
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  53. 2026-05-31 22:28 UTCEPSS rescore
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  55. 2026-05-31 00:14 UTCEPSS rescore
  56. 2026-05-29 13:41 UTCEPSS rescore
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  63. 2026-05-26 07:17 UTCEPSS rescore
  64. 2026-05-24 16:44 UTCEPSS rescore
  65. 2026-05-22 21:15 UTCEPSS rescore
  66. 2026-05-22 17:34 UTCEG score recompute
  67. 2026-05-22 17:34 UTCVendor advisory
  68. 2026-05-22 17:34 UTCGHSA enrichment
  69. 2026-05-20 22:37 UTCEPSS rescore
  70. 2026-05-20 22:37 UTCEPSS rescore
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  72. 2026-05-20 11:21 UTCEPSS rescore
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  74. 2026-05-18 21:30 UTCEPSS rescore
  75. 2026-05-18 21:30 UTCEPSS rescore

Publicly available exploits

(1 reference)

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

  • Exploit-DBEDB-40921✓ verified
    First seen Dec 15, 2016

    Nagios < 4.2.4 - Local Privilege Escalation

    Open source ↗

Frequently asked(5)

What is CVE-2016-9566?
CVE-2016-9566 is a high vulnerability published on December 15, 2016. base/logging.c in Nagios Core before 4.2.4 allows local users with access to an account in the nagios group to gain root privileges via a symlink attack on the log file. NOTE: this can be leveraged by remote attackers using CVE-2016-9565.
When was CVE-2016-9566 disclosed?
CVE-2016-9566 was first published in the National Vulnerability Database on December 15, 2016, with the most recent update on May 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-9566 actively exploited?
CVE-2016-9566 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 91.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-9566?
CVE-2016-9566 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2016-9566?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-9566, 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.

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