CVE-2026-11527: Config::IniFiles Command Injection and File Overwrite Vulnerability

Technical summary

The vulnerability exists in the _make_filehandle subroutine of Config::IniFiles. When a filename is passed via the -file argument (which flows through the documented ReadConfig method), the code opens it using two-argument open($fh, $filename) rather than safer alternatives like three-argument open($fh, '<', $filename). In Perl, the two-argument form treats leading pipes (|cmd or cmd|) as command execution and leading redirects (>, >>) as file truncation or append operations. An attacker supplying a crafted filename such as '| malicious_command' or '> /path/to/file' will cause unintended code execution or file destruction. Direct use of scalar references (-file => \$text) bypasses file opening entirely and is not affected.

Business impact

Organizations deploying Perl applications that use Config::IniFiles and accept user-supplied or external configuration file paths face remote code execution and data loss risks. Compromised systems could grant attackers command execution under the application's process UID, potentially leading to lateral movement, credential theft, or system compromise. File overwrite capabilities could corrupt application data or configuration. Scope is heightened in multi-tenant or web-facing applications where configuration paths might be influenced by user input.

Affected systems

Config::IniFiles versions before 3.001000 are vulnerable. Any Perl application or script that uses this library and passes untrusted input to the -file parameter is at risk. This includes web applications, automation frameworks, and system management tools built on Perl. In-memory scalar references are not affected. Organizations should audit their Perl codebase for Config::IniFiles usage and the source of file path arguments.

Exploitability

The vulnerability requires local access or the ability to influence a configuration file path passed to the application (user interaction is factored into the CVSS score). Exploitation is straightforward: an attacker crafts a filename with a leading pipe or redirect character and passes it to an application that forwards it to Config::IniFiles. No special privileges, complex exploitation techniques, or race conditions are needed. Once triggered, command execution runs with the application process's UID. The barrier to exploitation is low for attackers with any control over input fed to affected code paths.

Remediation

Upgrade Config::IniFiles to version 3.001000 or later. Vendors have patched the _make_filehandle routine to use the safer three-argument open() form. For applications that cannot immediately upgrade, implement input validation on configuration file paths: reject or sanitize any paths containing pipes, angle brackets, or other shell metacharacters before passing them to Config::IniFiles. Use allowlist-based path validation where possible. Audit logs for suspicious file path arguments or process spawning tied to configuration loading.

Patch guidance

Apply the latest Config::IniFiles release (3.001000 or later). On systems using Perl package managers, this typically requires running 'cpan Config::IniFiles' or updating via your distribution's package tool (apt, yum, etc.). Verify the installed version with 'perl -e "use Config::IniFiles; print $Config::IniFiles::VERSION"'. Test patched applications in a staging environment to confirm configuration loading behavior remains correct. If Config::IniFiles is vendored or embedded in an application, coordinate with the application vendor for a patched release.

Detection guidance

Monitor system logs and audit trails for signs of unusual process spawning or file operations triggered during configuration file loading. Look for application errors referencing _make_filehandle or file open failures with suspicious paths. Network detection is limited; focus on endpoint and application-level visibility. Check application code repositories and requirements files for Config::IniFiles pinned to versions before 3.001000. Review access logs for configuration file operations, particularly any referencing paths with pipe or redirect characters. Behavioral detection should flag unexpected command execution or file truncation following config reload operations.

Why prioritize this

This vulnerability merits immediate attention despite moderate attack surface constraints. The CVSS 8.6 HIGH score reflects high impact (command execution and file destruction) combined with low attack complexity. Organizations must prioritize based on whether their Perl applications accept external or user-influenced configuration file paths. Applications with strict, hardcoded configuration paths face lower practical risk. However, any web application, automation tool, or multi-tenant system using Config::IniFiles with dynamic path handling should be treated as critical-priority until patched.

Risk score, explained

CVSS 3.1 score of 8.6 (HIGH) reflects: Local attack vector (AV:L) since the attacker must provide input to the application or system; Low attack complexity (AC:L) because exploitation requires only crafted input with no special conditions; No privilege requirement (PR:N); User interaction required (UI:R) for the victim to process the malicious input; Changed scope (S:C) because the impact extends beyond the vulnerable component to the system; High confidentiality, integrity, and availability impact (C:H/I:H/A:H) from arbitrary command execution and file overwrites. The score appropriately captures a serious but not network-remotely-exploitable flaw.

Frequently asked questions