Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-28427 is a path traversal vulnerability in OpenDeck versions prior to 2.8.1. OpenDeck runs a webserver on port 57118 that serves static files for installed plugins but does not properly sanitize path components in HTTP requests. This allows an attacker to include "../" sequences in the request path to traverse outside the intended plugin directory and read arbitrary files accessible by the OpenDeck process.'}, {'type': 'paragraph', 'content': "The vulnerability arises because the server fails to correctly handle directory traversal sequences, enabling attackers to access sensitive files such as SSH private keys, AWS credentials, or browser profile data by crafting malicious requests. Exploitation requires knowledge of the victim's local username and user interaction, such as visiting a malicious webpage that makes requests to the local OpenDeck server."}, {'type': 'paragraph', 'content': 'This vulnerability is fixed in OpenDeck version 2.8.1 by enhancing path validation, canonicalizing requested paths, and enforcing that file access remains within the designated configuration directory.'}] [1]

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Impact Analysis

[{'type': 'paragraph', 'content': "This vulnerability can lead to unauthorized disclosure of sensitive files accessible by the OpenDeck process. An attacker can exploit it to read private keys, credentials, and other confidential configuration files from the victim's system."}, {'type': 'paragraph', 'content': "Such disclosure can result in further compromise of the victim's accounts or servers if the leaked credentials are used maliciously. The attack requires the victim to interact with a malicious webpage, which can then exfiltrate files from the local OpenDeck server without authentication."}, {'type': 'paragraph', 'content': 'The overall impact is moderate, with a CVSS v4 base score of 5.9, primarily affecting confidentiality. Integrity and availability are not impacted.'}] [1]

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by checking if the OpenDeck service is running a vulnerable version (prior to 2.8.1) and listening on port 57118. You can attempt to detect exploitation attempts by monitoring HTTP GET requests containing directory traversal sequences such as "../" targeting the OpenDeck webserver.'}, {'type': 'paragraph', 'content': 'A practical detection method is to use curl commands to simulate malicious requests that attempt to read sensitive files via path traversal. For example, you can run commands like:'}, {'type': 'list_item', 'content': 'curl "http://localhost:57118/{prefix}/../.ssh/id_rsa"'}, {'type': 'list_item', 'content': 'curl "http://localhost:57118/{prefix}/../.aws/credentials"'}, {'type': 'paragraph', 'content': 'Replace {prefix} with the appropriate plugin path prefix. If these requests return file contents, the system is vulnerable.'}, {'type': 'paragraph', 'content': 'Additionally, monitoring network traffic for suspicious requests containing encoded "../" sequences to port 57118 can help detect exploitation attempts.'}] [1]

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Mitigation Strategies

The immediate and most effective mitigation is to update OpenDeck to version 2.8.1 or later, where the vulnerability is fixed.

Other mitigation steps include:

• Ensure that the OpenDeck webserver properly sanitizes and canonicalizes requested paths to prevent directory traversal.
• Implement authentication mechanisms such as tokens to verify legitimate clients accessing the OpenDeck service.
• Restrict or disable Cross-Origin Resource Sharing (CORS) requests, especially reviewing and limiting permissive headers like Access-Control-Allow-Origin: *.

If updating immediately is not possible, consider restricting network access to port 57118 to trusted users only, and monitor for suspicious requests.

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