CVE-2026-41412 in alf.io
Summary
by MITRE • 06/03/2026
alf.io is an open source ticket reservation system for conferences, trade shows, workshops, and meetups. Prior to version 2.0-M5-2606, the alf.io extension sandbox injects a fully-functional HTTP client (`simpleHttpClient`) into every extension script's scope. The `postFileAndSaveResponse()` method accepts an arbitrary filesystem path as its `file` parameter and reads the file contents using `new FileInputStream(file)` with no path validation, directory restriction, or allowlist. A malicious extension script can read any file accessible to the JVM process user and exfiltrate it to an attacker-controlled server via HTTP POST. Version 2.0-M5-2606 patches the issue.
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Analysis
by VulDB Data Team • 06/03/2026
The alf.io ticket reservation system contains a critical security vulnerability in its extension sandbox implementation that affects versions prior to 2.0-M5-2606. This vulnerability stems from the improper handling of file system access within the extension execution environment, creating a severe path traversal and arbitrary file read condition. The system's extension sandbox provides a fully functional HTTP client named simpleHttpClient to every extension script, which when combined with the insecure file reading mechanism creates a dangerous attack vector for privilege escalation and data exfiltration.
The technical flaw manifests in the postFileAndSaveResponse() method which accepts an arbitrary filesystem path as input without any validation or restriction mechanisms. The implementation directly uses new FileInputStream(file) to read files, bypassing any directory restrictions or allowlists that should normally protect the system from unauthorized file access. This primitive implementation lacks input sanitization and path validation checks that would normally prevent access to files outside of designated directories or system resources. The vulnerability essentially allows any extension script to read any file accessible to the java virtual machine process user, regardless of the file's location or intended access restrictions.
The operational impact of this vulnerability is severe and far-reaching, particularly in multi-tenant environments where extension scripts may be provided by untrusted third parties. An attacker with the ability to upload or modify extension scripts can leverage this vulnerability to read sensitive configuration files, database credentials, application source code, user data, and system files that are accessible to the running JVM process. The vulnerability enables complete data exfiltration capabilities as malicious scripts can read files and POST their contents to attacker-controlled servers, potentially leading to full system compromise. This issue represents a classic case of insecure direct object reference combined with insufficient input validation, creating a path traversal vulnerability that can be exploited for privilege escalation.
The vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-73 (External Control of File Name or Path) classifications, demonstrating how improper input validation and lack of path restriction can lead to arbitrary file access. From an attack perspective, this vulnerability maps to multiple ATT&CK techniques including T1059.007 (Scripting), T1078.004 (Valid Accounts), and T1041 (Exfiltration Over C2 Channel). The security implications extend beyond simple data theft to include potential system compromise, as attackers can access system configuration files, application secrets, and potentially sensitive user data that may be stored in accessible locations.
The patch implemented in version 2.0-M5-2606 addresses this vulnerability by introducing proper path validation and directory restriction mechanisms within the extension sandbox. The fix likely involves implementing allowlists or denylists for file system access, enforcing directory restrictions, and adding input validation to prevent arbitrary path traversal. Organizations should immediately upgrade to version 2.0-M5-2606 or later to remediate this vulnerability. Additionally, system administrators should review and audit any existing extension scripts for potential malicious code, implement proper file access controls, and monitor for unauthorized file access patterns. The vulnerability highlights the importance of secure coding practices in sandboxed environments and demonstrates how seemingly benign features like HTTP client integration can create serious security risks when combined with insecure file system access patterns.