Is CVE-2016-9566 in the CISA KEV catalog?

No. CVE-2016-9566 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2016-9566?

CVE-2016-9566 has a CVSS v3 base score of 7.8 (HIGH).

What is the EPSS score for CVE-2016-9566?

CVE-2016-9566 has an EPSS score of 4.88% (91th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2016-9566?

Upgrade nagios3 on ubuntu 14.04 to 3.5.1-1ubuntu1.1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2016-9566

HIGHEPSS 91th pctl

7.8

CVSS v3

NVD

Description

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.

CWE-59Link Following CWE-264Permissions, Privileges, and Access Controls

How to fix

Remediation Available

nagios3Ubuntu

Fixed in:3.5.1-1ubuntu1.1USN-3253-1

Fixed in:3.5.1.dfsg-2.1ubuntu1.1USN-3253-1

nagios3-cgiUbuntu

Fixed in:3.5.1-1ubuntu1.1USN-3253-1

Fixed in:3.5.1.dfsg-2.1ubuntu1.1USN-3253-1

nagios3-coreUbuntu

Fixed in:3.5.1-1ubuntu1.1USN-3253-1

Fixed in:3.5.1.dfsg-2.1ubuntu1.1USN-3253-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

4.88%probability of exploitation in 30 days

91stpercentile

High risk: more likely to be exploited than 91% of all known CVEs.

References

Patch1

github.com

Exploit1

legalhackers.com

Vendor Advisory1

nagios.org

Third-Party Advisory2

Issue Tracking1

bugzilla.redhat.com

Other references12

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-06.