CVE-2006-2489 in Nagios
Summary
by MITRE
Integer overflow in CGI scripts in Nagios 1.x before 1.4.1 and 2.x before 2.3.1 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a content length (Content-Length) HTTP header. NOTE: this is a different vulnerability than CVE-2006-2162.
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Analysis
by VulDB Data Team • 06/22/2025
The vulnerability described in CVE-2006-2489 represents a critical integer overflow condition that affected Nagios monitoring systems across multiple versions including 1.x before 1.4.1 and 2.x before 2.3.1. This flaw specifically targeted CGI scripts within the Nagios framework, which are essential components responsible for web-based interface functionality and remote system management. The vulnerability manifests through improper handling of HTTP Content-Length headers, creating a scenario where malicious actors can manipulate input data to trigger system instability. The integer overflow occurs when the system processes excessively large content length values that exceed the maximum representable integer value, leading to unexpected behavior in the application's memory management and execution flow. This particular vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which is a well-documented weakness in software security where arithmetic operations produce values that exceed the maximum allowable range for the data type being used.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution, making it particularly dangerous for network infrastructure monitoring systems. When an attacker crafts a malicious Content-Length header value that triggers the integer overflow, the system may crash or behave unpredictably, resulting in complete service disruption. The crash occurs because the overflowed integer value can cause memory allocation failures or buffer overflows within the CGI script execution environment. In some cases, the overflowed value may also be used as a loop counter or buffer size parameter, potentially allowing attackers to manipulate program flow and execute arbitrary code on the target system. This vulnerability directly relates to the ATT&CK technique T1203, which involves exploitation of software vulnerabilities to gain unauthorized access or execute malicious code, and demonstrates how seemingly minor input validation flaws can lead to catastrophic system compromise.
The remediation strategy for this vulnerability requires immediate patching of affected Nagios installations to versions 1.4.1 and 2.3.1 or later, which contain proper input validation and integer overflow protection mechanisms. System administrators should implement comprehensive monitoring of HTTP headers and content length values to detect and block suspicious requests before they can trigger the vulnerability. Network segmentation and access controls should be strengthened to limit exposure of Nagios web interfaces to untrusted networks. Additionally, implementing proper input sanitization measures and ensuring that all integer operations within CGI scripts include overflow checking can prevent similar issues in other applications. Organizations should also consider deploying intrusion detection systems that can identify patterns associated with this specific attack vector and maintain regular vulnerability assessments to identify potential integer overflow issues in other software components. The fix implemented in subsequent Nagios versions typically involved adding bounds checking for content length values and proper handling of large integer values to prevent the overflow condition from occurring during normal operation.