CVE-2026-28427: OpenDeck Path Traversal Vulnerability

CVE-2026-28427 Overview

CVE-2026-28427 is a Path Traversal vulnerability affecting OpenDeck, a Linux software application for managing Elgato Stream Deck devices. Prior to version 2.8.1, the service listening on port 57118 serves static files for installed plugins but fails to properly sanitize path components. By including ../ sequences in the request path, an attacker can traverse outside the intended directory and read any file that OpenDeck can access on the system.

Critical Impact

Attackers can exploit this vulnerability to read sensitive files on the system, potentially exposing credentials, configuration files, and other sensitive data accessible by the OpenDeck service.

Affected Products

• OpenDeck versions prior to 2.8.1
• Linux systems running vulnerable OpenDeck installations
• Systems with OpenDeck service exposed on port 57118

Discovery Timeline

• 2026-03-04 - CVE-2026-28427 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28427

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as Path Traversal or Directory Traversal. The OpenDeck service hosts a web server on port 57118 that serves static files for installed plugins. The root cause lies in insufficient input validation when handling file path requests.

When the service receives a request for a file, it fails to properly sanitize path components before constructing the final file path. This allows an attacker to inject directory traversal sequences (../) into the request, escaping the intended plugin directory and accessing arbitrary files on the filesystem that the OpenDeck process has permissions to read.

Root Cause

The vulnerability stems from missing or inadequate path sanitization in the file serving logic. When handling requests for plugin static files, the application concatenates user-controlled path segments without validating that the resulting path remains within the intended directory. The lack of proper path canonicalization or directory containment checks enables traversal attacks.

Attack Vector

The attack is network-based and requires the attacker to send specially crafted HTTP requests to the OpenDeck service on port 57118. By including ../ sequences in the request path, an attacker can navigate up the directory tree and access files outside the plugin directory. For example, a request containing multiple ../ segments could potentially reach sensitive files such as /etc/passwd, configuration files, or application credentials.

The attack requires user interaction in some scenarios, as the service must be accessible to the attacker, either through local network access or if the port has been exposed externally. Successful exploitation could lead to information disclosure affecting confidentiality, with potential for further attacks based on exposed sensitive data.

Detection Methods for CVE-2026-28427

Indicators of Compromise

• HTTP requests to port 57118 containing ../ or URL-encoded variants (%2e%2e%2f) in the path
• Access log entries showing requests with unusual path patterns attempting to reach system files
• Unexpected file access patterns originating from the OpenDeck process
• Network traffic to port 57118 from unauthorized or external sources

Detection Strategies

• Monitor HTTP access logs for requests containing directory traversal sequences such as ../, ..%2f, or %2e%2e/
• Implement network-level detection rules to identify path traversal patterns in HTTP requests targeting port 57118
• Use file integrity monitoring to detect unauthorized access to sensitive files outside the OpenDeck plugin directory
• Deploy web application firewall rules to block requests with path traversal indicators

Monitoring Recommendations

• Enable verbose logging for the OpenDeck service to capture all incoming HTTP requests
• Configure network monitoring to alert on connections to port 57118 from untrusted networks
• Set up file access auditing for sensitive system files to detect unauthorized reads
• Implement alerting for anomalous file access patterns by the OpenDeck process

How to Mitigate CVE-2026-28427

Immediate Actions Required

• Upgrade OpenDeck to version 2.8.1 or later immediately
• Restrict network access to port 57118 using firewall rules to limit exposure to trusted hosts only
• Review system logs for any evidence of exploitation attempts
• Consider temporarily disabling the OpenDeck service until patching is complete if the service is exposed to untrusted networks

Patch Information

The vulnerability has been fixed in OpenDeck version 2.8.1. The patch implements proper path sanitization to prevent directory traversal attacks. Users should update to version 2.8.1 or later to remediate this vulnerability.

For detailed patch information, refer to the GitHub commit and the GitHub Security Advisory.

Workarounds

• Use firewall rules to restrict access to port 57118 to localhost only if remote access is not required
• Deploy a reverse proxy with path sanitization in front of the OpenDeck service
• Run OpenDeck under a restricted user account with minimal file system permissions to limit the impact of potential exploitation
• Consider network segmentation to isolate the system running OpenDeck from sensitive network resources

# Example: Restrict port 57118 to localhost only using iptables
iptables -A INPUT -p tcp --dport 57118 -s 127.0.0.1 -j ACCEPT
iptables -A INPUT -p tcp --dport 57118 -j DROP