CVE-2016-9566

HIGH

Nagios < 4.2.3 - Privilege Escalation via Symlink Attack on Log File

Title source: llm

Exploitation Summary

EIP tracks 1 public exploit for CVE-2016-9566. PoCs published by Dawid Golunski.

AI-analyzed exploit summary This exploit leverages a symlink attack on Nagios Core's log file to manipulate `/etc/ld.so.preload` and escalate privileges to root. It compiles a shared library to set SUID permissions on a backdoor shell when executed by a SUID binary like `sudo`.

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.

Exploits (1)

exploitdb WORKING POC VERIFIED

by Dawid Golunski · bashlocallinux

https://www.exploit-db.com/exploits/40921

View Code ZIP pw:eip

This exploit leverages a symlink attack on Nagios Core's log file to manipulate `/etc/ld.so.preload` and escalate privileges to root. It compiles a shared library to set SUID permissions on a backdoor shell when executed by a SUID binary like `sudo`.

Classification

Working Poc 100%

Attack Type

Lpe

Complexity

Moderate

Reliability

Reliable

Target: Nagios Core < 4.2.4

Auth required

Prerequisites: Access to 'nagios' user or group · Write permissions to Nagios log directory · GCC to compile the shared library

MITRE ATT&CK

T1548.001 - Setuid and Setgid T1574.006 - Dynamic Linker Hijacking

devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (18)

Core 18

Core References

Third Party Advisory vendor-advisory x_refsource_gentoo

https://security.gentoo.org/glsa/201710-20

Exploit, Third Party Advisory exploit x_refsource_exploit-db

https://www.exploit-db.com/exploits/40921/

Third Party Advisory, VDB Entry vdb-entry x_refsource_bid

http://www.securityfocus.com/bid/94919

Issue Tracking, Patch x_refsource_confirm

https://github.com/NagiosEnterprises/nagioscore/commit/c29557dec91eba2306f5fb11b8da4474ba63f8c4

View Patch ZIP pw:eip

Vendor Advisory vendor-advisory x_refsource_redhat

http://rhn.redhat.com/errata/RHSA-2017-0258.html

Third Party Advisory vendor-advisory x_refsource_gentoo

https://security.gentoo.org/glsa/201612-51

Vendor Advisory vendor-advisory x_refsource_redhat

http://rhn.redhat.com/errata/RHSA-2017-0212.html

Vendor Advisory vendor-advisory x_refsource_redhat

http://rhn.redhat.com/errata/RHSA-2017-0213.html

Vendor Advisory x_refsource_confirm

https://www.nagios.org/projects/nagios-core/history/4x/

Third Party Advisory vendor-advisory x_refsource_gentoo

https://security.gentoo.org/glsa/201702-26

Mailing List mailing-list x_refsource_mlist

https://lists.debian.org/debian-lts-announce/2018/12/msg00014.html

Vendor Advisory vendor-advisory x_refsource_redhat

http://rhn.redhat.com/errata/RHSA-2017-0259.html

Third Party Advisory, VDB Entry vdb-entry x_refsource_sectrack

http://www.securitytracker.com/id/1037487

Mailing List, Third Party Advisory mailing-list x_refsource_fulldisc

http://seclists.org/fulldisclosure/2016/Dec/58

Issue Tracking x_refsource_confirm

https://bugzilla.redhat.com/show_bug.cgi?id=1402869

Exploit, Third Party Advisory x_refsource_misc

https://legalhackers.com/advisories/Nagios-Exploit-Root-PrivEsc-CVE-2016-9566.html

Vendor Advisory vendor-advisory x_refsource_redhat

http://rhn.redhat.com/errata/RHSA-2017-0214.html

Vendor Advisory vendor-advisory x_refsource_redhat

http://rhn.redhat.com/errata/RHSA-2017-0211.html

Scores

CVSS v3 7.8

EPSS 0.0488

EPSS Percentile 90.9%

Attack Vector LOCAL

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

Details

CWE

CWE-264 CWE-59

Status published

Products (1)

nagios/nagios < 4.2.3

Published Dec 15, 2016

Tracked Since Feb 18, 2026