Nagios XI 5.7.5 Remote OS Command Injection Vulnerability (CVE-2021-25297) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTNagios XI version 5.7.5
An authenticated attacker can execute arbitrary OS commands on the Nagios XI server via a single crafted HTTP request, potentially leading to full system compromise.
Immediately upgrade to the latest patched version of Nagios XI, and restrict access to the vulnerable configuration wizard path.
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Upgrade Nagios XI to the latest secure release. You can download and run the official upgrade script using the following commands:
# Download and execute the Nagios XI upgrade script
cd /tmp
wget https://assets.nagios.com/downloads/nagiosxi/xi-latest.tar.gz
tar xzf xi-latest.tar.gz
cd nagiosxi
./upgrade2. Temporary Workaround & Hardening Configuration
If patching cannot be applied immediately, restrict access to the vulnerable Switch wizard directory or configure your Web Application Firewall (WAF) to block requests containing shell metacharacters targeting the path.
# Nginx configuration example: Restricting access to the vulnerable path
location /nagiosxi/includes/configwizards/switch/ {
allow 10.0.0.0/8;
deny all;
}3. Log Audit & IoC Verification Commands
Verify the currently installed Nagios XI version and inspect the web server access logs for any suspicious command injection attempts targeting switch.inc.php.
# 1. Check the installed Nagios XI version
grep 'product_version' /usr/local/nagiosxi/html/config.inc.php
# 2. Search Apache access logs for suspicious requests targeting switch.inc.php
grep -i 'switch.inc.php' /var/log/httpd/access_log | grep -E '(%3B|%26|%7C|;|\&|\|)'Block Exploits Instantly with Managed Virtual Patching Rules
Can't patch production immediately? Deploy managed WAF rules at the edge to intercept RCE, SQLi, and deserialization payloads before they hit your origin server.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-25297) is an OS command injection flaw in Nagios XI, a widely used network monitoring solution. The root cause lies within the /usr/local/nagiosxi/html/includes/configwizards/switch/switch.inc.php script, which fails to properly sanitize and escape authenticated user-controlled input before passing it to system shell execution functions. This allows an authenticated user to inject arbitrary shell commands via a single HTTP request.
2. Exploitation Mechanics & Attack Scenario
To exploit this vulnerability, an attacker must first obtain valid credentials (even with low privileges) to access the Nagios XI web interface. The attacker then targets the Switch Config Wizard by sending a crafted HTTP POST or GET request containing shell metacharacters (such as ;, &&, or |) followed by malicious OS commands within the parameters. Because the PHP script executes these parameters directly in the system shell, the injected commands run with the privileges of the web server user (typically apache or nagios), enabling remote code execution.
3. Infrastructure & Business Impact
Since Nagios XI servers typically hold extensive monitoring privileges across enterprise networks, a compromise of this system is highly critical. Attackers can leverage the established foothold to harvest internal network credentials, map infrastructure topology, and perform lateral movement. Given that this vulnerability is actively exploited in the wild and listed in the CISA KEV catalog, failure to remediate poses an immediate threat of full network compromise.
Official Vendor Advisories & References
Nagios XI version xi-5.7.5 is affected by OS command injection. The vulnerability exists in the file /usr/local/nagiosxi/html/includes/configwizards/switch/switch.inc.php due to improper sanitization of authenticated user-controlled input by a single HTTP request, which can lead to OS command injection on the Nagios XI server.
Frequently Asked SecOps Questions (CVE-2021-25297)
FAQQ1. How critical is CVE-2021-25297 and is it actively exploited in the wild?
CVE-2021-25297 is rated CVSS 8.8 (HIGH) with a 30-day EPSS exploitation probability of 56.7%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-25297?
Primary impacted vendors include nagios across nagios_xi. Scope summary: Nagios XI version 5.7.5
Q3. What temporary mitigations or workarounds exist for CVE-2021-25297 before patching?
[Mitigation] Immediately upgrade to the latest patched version of Nagios XI, and restrict access to the vulnerable configuration wizard path. Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-25297
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