CVE-2026-55552 in Yamcs
Summary
by MITRE • 08/28/2026
Yamcs is a mission control framework. Prior to 5.11.13, Yamcs StaticFileHandler.locateFile resolves an unauthenticated request path without using Path.normalize and Path.toAbsolutePath to confirm that the absolute path remains within the configured staticRoots. A path containing traversal segments can escape the intended web root and return an arbitrary readable host file. The flaw is in yamcs-core/src/main/java/org/yamcs/http/StaticFileHandler.java and can disclose sensitive operating-system and application data. This issue is fixed in version 5.11.13, and the 5.12 line is fixed from version 5.12.0.
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability identified within Yamcs versions prior to 5.11.13 represents a critical path traversal flaw located in the StaticFileHandler component of the yamcs-core module. As a mission control framework, Yamcs is responsible for managing and monitoring complex systems, often handling sensitive operational data and configuration files. The core technical deficiency lies in how the locateFile method processes incoming request paths from unauthenticated users. Specifically, the implementation fails to utilize Path.normalize or Path.toAbsolutePath methods to validate that the resolved file path remains strictly within the boundaries of the configured staticRoots directory. This oversight allows an attacker to manipulate input parameters containing directory traversal sequences, such as dot-dot-slash characters, which are not properly sanitized before being used to locate files on the host system.
From a technical perspective, this flaw is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The absence of robust path canonicalization means that relative paths provided by an attacker can resolve to absolute locations outside the intended web root. When the server processes these maliciously crafted requests, it bypasses the security controls designed to isolate static content from the rest of the file system. Consequently, this leads to CWE-200: Exposure of Sensitive Information to an Unauthorized Actor. The operational impact is severe, as successful exploitation enables arbitrary read access to files on the host operating system and application directories. An attacker could potentially retrieve configuration files containing credentials, private keys, or other sensitive data that were not intended for public exposure via the web interface.
This vulnerability aligns with ATT&CK technique T1083: File and Directory Discovery, where adversaries use file directory commands to explore a compromised system. In the context of Yamcs, this capability could serve as an initial vector for further reconnaissance or data exfiltration in industrial control environments. The lack of authentication requirements exacerbates the risk, allowing any network-accessible user to attempt exploitation without needing valid credentials first. This significantly lowers the barrier to entry for attackers seeking to compromise the integrity and confidentiality of the mission control infrastructure.
To mitigate this vulnerability, organizations running Yamcs must upgrade immediately to version 5.11.13 or later in the 5.11 line, or to version 5.12.0 and above in the newer release track. These versions include patches that enforce strict path validation using standard Java NIO Path methods to ensure all requested files reside within the designated static roots. Additionally, administrators should implement defense-in-depth strategies by configuring web servers to serve static content from isolated directories with minimal permissions. Regular security audits of file handling logic and adherence to secure coding standards are recommended to prevent similar directory traversal issues in future development cycles.