CVE-2026-13509: RAGapp Path Traversal Vulnerability

CVE-2026-13509 Overview

CVE-2026-13509 is a path traversal vulnerability in RAGapp versions up to 0.1.5. The flaw resides in the FileHandler.upload_file and FileHandler.remove_file functions within src/ragapp/backend/controllers/files.py, part of the Knowledge File Handler component. Attackers can manipulate file path inputs to reference locations outside the intended directory. The issue is classified under CWE-22 (Improper Limitation of a Pathname to a Restricted Directory). The exploit has been publicly disclosed, and a pull request to fix the issue is awaiting acceptance from the maintainers.

Critical Impact
Authenticated remote attackers can read, write, or delete files outside the intended knowledge base directory, potentially affecting application integrity and confidentiality.

Affected Products

RAGapp versions up to and including 0.1.5
Component: Knowledge File Handler (src/ragapp/backend/controllers/files.py)
Functions: FileHandler.upload_file and FileHandler.remove_file

Discovery Timeline

2026-06-28 - CVE-2026-13509 published to NVD
2026-06-29 - Last updated in NVD database

Technical Details for CVE-2026-13509

Vulnerability Analysis

The vulnerability affects RAGapp, an open-source application for building Retrieval-Augmented Generation (RAG) workflows. The Knowledge File Handler component accepts file names or paths from remote users and passes them to file system operations without sufficient validation. An authenticated attacker with low privileges can supply crafted path segments containing traversal sequences such as ../ to escape the intended upload directory.

The impact spans confidentiality, integrity, and availability at a limited level. Attackers may overwrite files in unintended locations via upload_file or delete arbitrary files reachable by the application process via remove_file. Because RAGapp typically runs with access to configuration, model data, and knowledge base contents, exploitation can disrupt RAG pipeline operations. The EPSS score is 0.294% with a percentile of 21.177, indicating a relatively low exploitation probability in the near term.

Root Cause

The root cause is missing canonicalization and validation of user-supplied file identifiers before they are joined with the base storage path. The affected functions concatenate untrusted input into filesystem paths without confirming that the resolved path remains inside the designated knowledge file directory.

Attack Vector

Exploitation occurs over the network against the RAGapp HTTP interface. The attacker requires low-level authenticated access to invoke the file handler endpoints. By submitting a filename containing directory traversal sequences to the upload or remove endpoint, the attacker forces the application to operate on files outside the intended directory. See GitHub Issue #293 for the original disclosure.

No verified proof-of-concept code has been released as part of this advisory. The vulnerability mechanism is described in the VulDB CVE-2026-13509 entry.

Detection Methods for CVE-2026-13509

Indicators of Compromise

HTTP requests to RAGapp file handler endpoints containing ../, ..\, or URL-encoded traversal sequences such as %2e%2e%2f.
Unexpected file creation, modification, or deletion outside the configured knowledge base directory.
Application log entries showing FileHandler.upload_file or FileHandler.remove_file operating on absolute paths or paths containing parent directory references.

Detection Strategies

Inspect web server and application logs for filename parameters containing traversal patterns targeting /files or knowledge upload routes.
Monitor filesystem activity on hosts running RAGapp for write and delete operations by the application process outside its designated data directory.
Deploy web application firewall rules that flag path traversal payloads in multipart file upload requests.

Monitoring Recommendations

Enable verbose logging on the RAGapp backend to capture the resolved absolute path for every file handler operation.
Alert on any HTTP 200 response from file handler endpoints where the request body or query includes encoded or literal parent directory traversal tokens.
Baseline expected file paths for the knowledge store and alert on deviations.

How to Mitigate CVE-2026-13509

Immediate Actions Required

Restrict network access to RAGapp instances so that only trusted, authenticated users can reach the file handler endpoints.
Audit the knowledge base directory and application filesystem for signs of unauthorized file modification or deletion.
Rotate any credentials or API keys stored on hosts running vulnerable RAGapp versions if unauthorized file access is suspected.

Patch Information

A fix has been proposed in GitHub Pull Request #294 but has not yet been merged at the time of publication. Administrators should track the RAGapp repository and apply the fix once it is released in an upstream version beyond 0.1.5.

Workarounds

Apply the patch from PR #294 manually to src/ragapp/backend/controllers/files.py after validating the change against the official repository.
Enforce filename validation at a reverse proxy by rejecting requests containing .., backslashes, or URL-encoded traversal sequences in file upload parameters.
Run RAGapp under a dedicated low-privilege user account with filesystem access limited to the knowledge base directory using OS-level access controls or containerization.

bash

# Example nginx rule to block traversal patterns in RAGapp file endpoints
location /api/files {
    if ($request_uri ~* "(\.\./|\.\.\\|%2e%2e%2f|%2e%2e/)") {
        return 403;
    }
    proxy_pass http://ragapp_backend;
}