CVE-2026-26102: Owl OPDS Privilege Escalation Vulnerability

CVE-2026-26102 Overview

CVE-2026-26102 is an Incorrect Permission Assignment for Critical Resource vulnerability in Owl opds version 2.2.0.4. This flaw allows attackers to manipulate files through crafted network requests, potentially leading to unauthorized access to sensitive resources, data tampering, or system compromise.

Critical Impact

Attackers with local access can exploit improper permission assignments to manipulate critical files, potentially leading to unauthorized data modification, privilege escalation, or compromise of system integrity.

Affected Products

• Owl opds 2.2.0.4

Discovery Timeline

• February 20, 2026 - CVE-2026-26102 published to NVD
• February 20, 2026 - Last updated in NVD database

Technical Details for CVE-2026-26102

Vulnerability Analysis

This vulnerability falls under CWE-732 (Incorrect Permission Assignment for Critical Resource), a common security weakness where software fails to properly set or maintain access permissions on critical resources. In the context of Owl opds 2.2.0.4, the application does not adequately restrict access to sensitive files or directories, allowing low-privileged users to perform unauthorized file manipulation operations.

The vulnerability requires local access to exploit, meaning an attacker must already have some level of access to the target system. However, once exploited, the impact is significant—affecting confidentiality, integrity, and availability of the targeted resources. The attack can be executed with low complexity and does not require user interaction, making it a practical threat in environments where multiple users have access to systems running vulnerable Owl opds installations.

Root Cause

The root cause of CVE-2026-26102 is the failure of Owl opds to properly assign and enforce access permissions on critical resources. When the application creates, modifies, or accesses files, it does not adequately restrict which users can perform these operations. This incorrect permission assignment allows unauthorized users to interact with files that should be protected, bypassing intended access controls.

Common manifestations of CWE-732 include:

• Files created with overly permissive modes (e.g., world-writable)
• Missing access control checks before file operations
• Improper inheritance of permissions from parent directories
• Failure to drop privileges when accessing sensitive resources

Attack Vector

The attack vector for CVE-2026-26102 involves sending crafted network requests to the vulnerable Owl opds instance. Although classified as a local attack vector, the exploitation mechanism leverages network request handling within the application.

An attacker with local system access can craft malicious requests that exploit the improper permission assignments. The exploitation flow typically involves:

1. Identifying target files or resources with incorrect permissions
2. Crafting network requests that trigger file manipulation operations
3. Exploiting the lack of proper permission checks to read, modify, or delete protected files
4. Achieving unauthorized access to sensitive data or system configurations

For detailed technical information about this vulnerability, refer to the Nozomi Networks Vulnerability Advisory.

Detection Methods for CVE-2026-26102

Indicators of Compromise

• Unexpected file permission changes on resources managed by Owl opds
• Anomalous file access patterns or modifications to configuration files
• Unusual network requests targeting the Owl opds service
• Log entries indicating unauthorized file operations or access attempts

Detection Strategies

• Monitor file system integrity for unauthorized modifications to Owl opds configuration and data files
• Implement network traffic analysis to detect crafted requests targeting the vulnerable endpoints
• Deploy endpoint detection solutions to identify anomalous file permission changes
• Review application logs for unusual request patterns or error messages related to file access

Monitoring Recommendations

• Enable detailed logging for Owl opds file operations and network requests
• Configure file integrity monitoring (FIM) on directories containing critical Owl opds resources
• Set up alerts for privilege escalation attempts or unauthorized access to protected files
• Implement network-level monitoring to detect exploitation attempts

How to Mitigate CVE-2026-26102

Immediate Actions Required

• Identify all systems running Owl opds version 2.2.0.4 and assess exposure
• Restrict network access to Owl opds services using firewall rules or network segmentation
• Review and harden file system permissions on Owl opds installation directories
• Limit local access to systems running the vulnerable software to trusted users only

Patch Information

At the time of publication, check the Nozomi Networks Vulnerability Advisory for the latest patch information and vendor guidance. Monitor official Owl opds release channels for security updates addressing this vulnerability.

Workarounds

• Apply restrictive file system permissions (e.g., chmod 600) on critical Owl opds resources manually
• Implement network access controls to limit which hosts can communicate with Owl opds services
• Deploy application-level access controls or reverse proxy configurations to filter malicious requests
• Consider running Owl opds in a sandboxed or containerized environment to limit the impact of exploitation

# Example: Restrict file permissions on Owl opds configuration directory
chmod -R 600 /path/to/owlopds/config/
chown -R owlopds:owlopds /path/to/owlopds/config/

# Example: Limit network access using iptables
iptables -A INPUT -p tcp --dport <owlopds_port> -s 127.0.0.1 -j ACCEPT
iptables -A INPUT -p tcp --dport <owlopds_port> -j DROP