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Nagios CVE-2026-2043

HIGH
OS Command Injection (CWE-78)
2026-02-20 zdi-disclosures@trendmicro.com
8.8
CVSS 3.1 · NVD
View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate to Nagios Host interface
  2. Exploit
    Call esensors_websensor_configwizard_func method
  3. Execution
    Inject shell metacharacters in user-supplied string
  4. Impact
    Execute arbitrary code as service account

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization OS command sanitization, avoid shell exec
MITRE ATT&CK

2 techniques across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Valid authentication credentials for Nagios Host required. Attacker must access the esensors_websensor_configwizard_func function through the web interface. Command injection occurs in user-supplied string parameter passed to system call execution.

Impact

CVSS 8.8 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Exploitable via remote/network.

Exploit ScenarioDerived

A remote attacker could exploit this vulnerability to execute arbitrary code on affected installations of Nagios Host.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 1.2% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Remote code execution in Nagios Xi through command injection in the esensors_websensor_configwizard_func method allows authenticated attackers to execute arbitrary commands with service account privileges. The vulnerability stems from insufficient input validation on user-supplied parameters passed to system calls. With a CVSS score of 8.8 and no patch currently available, this poses a significant risk to authenticated users of affected Nagios installations.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 22:04 CVSS 8.8

Nagios Host esensors_websensor_configwizard_func Command Injection Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Nagios Host. [CVSS 8.8 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-78 (OS Command Injection). Affects the context of the component of Nagios Xi. Nagios Host esensors_websensor_configwizard_func Command Injection Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Nagios Host. Authentication is required to exploit this vulnerability.

The specific flaw exists within the esensors_websensor_configwizard_func method. The issue results from the lack of proper validation of a user-supplied string before using it to execute a system call. An attacker can leverage

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Nagios Host esensors_websensor_configwizard_func Command Injection Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Nagios Host. Authentication is required to exploit this vulnerability.

The specific flaw exists within the esensors_websensor_configwizard_func method. The issue results from the lack of proper validation of a user-supplied string before using it to execute a system call. An attacker can leverage this vulnerability to execute code in the context of the service account. Was ZDI-CAN-28249.

Executive ViewAI

Why It Matters

A critical remote code execution vulnerability (CVE-2026-2043) has been discovered in Nagios Host monitoring systems with no vendor patch currently available. Attackers can exploit this flaw to gain unauthorized access and control of affected monitoring infrastructure, potentially compromising visibility into critical IT systems and enabling lateral movement throughout the network.

Business Impact: High
Compensating Controls
  1. Disable esensors_websensor_configwizard_func feature immediately if operationally feasible. 2) Implement network segmentation restricting Nagios Host access to trusted internal networks only. 3) Deploy WAF rules to block malicious command injection patterns targeting the vulnerable endpoint. 4) Enable comprehensive logging and monitoring of all access to Nagios Host systems. 5) Require multi-factor authentication for administrative access. 6) Monitor vendor security advisories closely for patch availability.

Threat Intelligence Overview

EPSS Score
1.2%
Top 22% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 1.2%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
High

Priority Score

45
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

OS command injection occurs when an application passes unsanitized user input directly into system shell commands.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)CVE.org

cpe:2.3:a:nagios:nagios_xi:2026:r1:*:*:*:*:*:*

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