CVE-2025-63261: AWStats 8.0 RCE Vulnerability

CVE-2025-63261 Overview

CVE-2025-63261 is a command injection vulnerability affecting AWStats 8.0, a widely-used open-source web analytics tool. The vulnerability exists in the Perl open function implementation within the AWStats codebase, allowing attackers with local access to inject and execute arbitrary system commands. This flaw falls under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), representing a significant security risk for systems running vulnerable AWStats installations.

Critical Impact

Successful exploitation allows local attackers to execute arbitrary commands with the privileges of the AWStats process, potentially leading to full system compromise, data exfiltration, or lateral movement within the network.

Affected Products

• AWStats 8.0

Discovery Timeline

• 2026-03-20 - CVE-2025-63261 published to NVD
• 2026-03-25 - Last updated in NVD database

Technical Details for CVE-2025-63261

Vulnerability Analysis

This command injection vulnerability stems from improper handling of user-controlled input passed to Perl's open function within the AWStats 8.0 codebase. The vulnerability requires local access to exploit, meaning an attacker must already have some level of access to the target system. Once exploited, the vulnerability can result in complete compromise of confidentiality, integrity, and availability of the affected system.

The attack does not require user interaction, making it particularly dangerous in environments where AWStats is deployed with insufficient access controls. Successful exploitation enables attackers to execute commands with the same privileges as the AWStats process, which may include elevated permissions depending on the deployment configuration.

Root Cause

The root cause of CVE-2025-63261 lies in the unsafe use of Perl's two-argument open function. When user-supplied input is passed directly to open() without proper sanitization, special characters such as pipes (|) can be interpreted as shell commands rather than file paths. This classic Perl security anti-pattern allows attackers to inject arbitrary shell commands that will be executed by the underlying operating system.

AWStats, written in Perl, processes various configuration parameters and log file inputs. When these inputs are not properly validated before being passed to file operations, command injection becomes possible.

Attack Vector

The attack vector is local, requiring the attacker to have existing access to the system where AWStats is installed. The attacker can craft malicious input containing shell metacharacters that, when processed by the vulnerable open function call, results in command execution. This could be accomplished through:

• Manipulating configuration files that AWStats reads
• Injecting malicious content into log files processed by AWStats
• Exploiting any interface that allows parameter passing to the vulnerable code path

The vulnerability does not require elevated privileges to exploit, though the impact depends on the privilege level of the AWStats process. For detailed technical analysis, see the Pentest Tools Vulnerability Report.

Detection Methods for CVE-2025-63261

Indicators of Compromise

• Unexpected child processes spawned by the AWStats Perl process (awstats.pl)
• Suspicious command-line arguments containing shell metacharacters in AWStats-related processes
• Anomalous file access patterns from the AWStats process, particularly to sensitive system files
• Unusual network connections originating from the AWStats process

Detection Strategies

• Monitor process execution trees for unexpected commands spawned by awstats.pl or its parent web server process
• Implement file integrity monitoring on AWStats configuration files and the awstats.pl script itself
• Deploy SIEM rules to detect shell metacharacters (pipe |, backticks, $()) in AWStats log entries
• Use endpoint detection and response (EDR) solutions to identify command injection patterns

Monitoring Recommendations

• Enable comprehensive logging for AWStats operations and review logs for suspicious patterns
• Configure audit rules to track execve system calls from processes associated with AWStats
• Implement behavioral analysis to detect deviation from normal AWStats process activity
• Set up alerts for any attempts to execute system commands through the AWStats process context

How to Mitigate CVE-2025-63261

Immediate Actions Required

• Identify all AWStats 8.0 installations in your environment and assess exposure
• Restrict local access to systems running AWStats to only authorized personnel
• Apply the principle of least privilege to the AWStats process and its associated service account
• Monitor for any signs of exploitation while awaiting or applying patches

Patch Information

System administrators should review the Debian LTS Security Announcement for distribution-specific patch information and updates. Additionally, consult the AWStats source repository for any upstream fixes that may be available.

Organizations running AWStats on Debian-based systems should apply security updates as they become available through their package manager.

Workarounds

• Run AWStats in a sandboxed or containerized environment to limit the blast radius of potential exploitation
• Implement strict input validation on any configuration files or parameters processed by AWStats
• Remove or disable AWStats if it is not actively required in your environment
• Use application-level firewalls or security modules to filter potentially malicious input before it reaches AWStats

# Restrict AWStats execution permissions
chmod 750 /usr/lib/cgi-bin/awstats.pl
chown root:www-data /usr/lib/cgi-bin/awstats.pl

# Ensure AWStats config files are only writable by root
chmod 644 /etc/awstats/awstats.*.conf
chown root:root /etc/awstats/awstats.*.conf