CVE-2026-78381 in RansomLook
Summary
by MITRE • 08/24/2026
RansomLook contains a path traversal vulnerability in the handling of the screen field associated with group posts. The GroupPost.get API handler concatenates the database-controlled screen value directly with the application's source/ directory and opens the resulting path without verifying that the resolved file remains within the intended directory.
Because the screen field is free-form and can be populated either through the administrative post editor or through data imported from a remote RansomLook instance, a malicious upstream instance can provide traversal sequences such as ../config/generic.json. When the affected post is subsequently retrieved through the API, RansomLook resolves and reads the attacker-controlled path and returns the contents of the referenced file Base64-encoded in the API response.
This can allow an attacker (being admin) controlling imported post data to read arbitrary files accessible to the RansomLook process, potentially exposing sensitive configuration data, API credentials, password hashes, or other application secrets. The attack does not require the malicious upstream to possess an account on the affected RansomLook instance.
The vulnerability is addressed by resolving screen paths with os.path.realpath() and verifying that the resolved path remains beneath the application's source/ directory. Validation is performed both when values are written and immediately before files are read. Using canonical paths also prevents traversal through symbolic links that would bypass purely lexical path normalization checks.
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Analysis
by VulDB Data Team • 08/24/2026
The identified vulnerability in RansomLook constitutes a critical Path Traversal flaw within the GroupPost.get API handler, specifically affecting the processing of the screen field associated with group posts. This security defect arises from improper input validation and unsafe file system operations where the application concatenates user-controlled or database-stored values directly into file paths without adequate sanitization. The core technical failure lies in the lack of verification that the resulting resolved path remains within the intended directory boundaries, allowing an attacker to manipulate the file access mechanism to read arbitrary files from the server's filesystem. This type of vulnerability is classically categorized under CWE-22: Improper Limitation of a Pathname to a Restricted Directory and aligns with MITRE ATT&CK technique T1083: File and Directory Discovery, as it enables unauthorized enumeration and retrieval of sensitive system data.
The operational impact of this flaw is significant because the screen field serves as an entry point for file path resolution that can be influenced by external actors. The vulnerability allows a malicious actor who has administrative privileges or control over imported post data to inject traversal sequences such as ../config/generic.json into the database fields. When the affected post is subsequently retrieved via the API, RansomLook resolves this manipulated path and reads the contents of the referenced file. Crucially, these contents are returned Base64-encoded within the API response, effectively creating a remote arbitrary file read vulnerability. This mechanism does not require the attacker to possess an account on the target instance if they can influence data imported from a compromised upstream RansomLook instance, thereby expanding the attack surface beyond direct authentication vectors and enabling privilege escalation through information disclosure.
The exploitation of this flaw allows attackers to exfiltrate sensitive configuration files, API credentials, password hashes, and other application secrets that are accessible to the process running RansomLook. The exposure of such data can lead to further compromise of the infrastructure, including lateral movement or complete system takeover depending on the permissions held by the service account. To mitigate this vulnerability, developers must implement robust path normalization techniques. Specifically, resolving screen paths using os.path.realpath() ensures that symbolic links and relative directory traversals are canonicalized before access is granted. Furthermore, validation logic must be applied both when values are written to the database and immediately prior to file read operations to ensure the resolved absolute path remains strictly beneath the application's source/ directory. This dual-layered defense in depth approach prevents attackers from bypassing lexical checks through symbolic links or other filesystem tricks, thereby securing the integrity of the file access mechanism against traversal attacks.