CVE-2026-7315: Spire PDF MCP Server Path Traversal Flaw

CVE-2026-7315 Overview

A path traversal vulnerability has been discovered in eiceblue spire-pdf-mcp-server version 0.1.1. This security flaw affects the get_pdf_path function within the src/spire_pdf_mcp/server.py file of the PDF File Handler component. By manipulating the filepath argument, an attacker can traverse directories and potentially access files outside the intended directory structure. The vulnerability is remotely exploitable, and exploit details have been publicly disclosed.

Critical Impact

Remote attackers can exploit this path traversal vulnerability to read arbitrary files on the server, potentially exposing sensitive configuration data, credentials, or other confidential information stored on the affected system.

Affected Products

• eiceblue spire-pdf-mcp-server version 0.1.1
• Systems running the vulnerable PDF File Handler component
• Deployments with network-accessible spire-pdf-mcp-server instances

Discovery Timeline

• 2026-04-28 - CVE-2026-7315 published to NVD
• 2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-7315

Vulnerability Analysis

This path traversal vulnerability (CWE-22) exists in the PDF File Handler component of spire-pdf-mcp-server. The get_pdf_path function in src/spire_pdf_mcp/server.py fails to properly sanitize or validate the filepath argument before processing file operations. This allows attackers to supply specially crafted path sequences that escape the intended directory context.

The vulnerability is network-accessible, meaning attackers do not require local access to exploit this flaw. No authentication appears to be required to trigger the vulnerable code path, and no user interaction is needed for successful exploitation. An exploit has been published and may be actively used against vulnerable installations.

The project maintainers were notified through a GitHub issue, but have not yet responded to the security report.

Root Cause

The root cause of this vulnerability is improper input validation within the get_pdf_path function. The function accepts a user-controlled filepath parameter without adequately sanitizing path traversal sequences such as ../ or similar constructs. This allows an attacker to construct malicious file paths that reference files and directories outside the intended working directory.

The lack of canonicalization and boundary checking enables directory escape attacks, where relative path components are processed without verification against an allowed base directory.

Attack Vector

The attack vector for CVE-2026-7315 is network-based. An attacker can remotely send malicious requests to the spire-pdf-mcp-server containing crafted filepath values with directory traversal sequences. By including sequences like ../ in the filepath parameter, the attacker can navigate outside the application's designated file directory and access arbitrary files on the server filesystem.

A typical exploitation scenario involves sending requests with path manipulation patterns such as ../../etc/passwd or ..\..\windows\system32\config\sam depending on the target operating system. The server processes these paths without proper validation, resulting in unauthorized file access.

For technical details and the publicly disclosed exploit, refer to the VulDB entry and the GitHub issue tracking.

Detection Methods for CVE-2026-7315

Indicators of Compromise

• HTTP requests or API calls containing path traversal sequences (../, ..\, %2e%2e%2f) in filepath parameters
• Unexpected file access attempts targeting sensitive system files outside the PDF directory
• Log entries showing requests for files in parent directories or system paths
• Unusual read operations on configuration files, password files, or other sensitive data

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block path traversal patterns in request parameters
• Monitor application logs for filepath parameters containing directory traversal sequences
• Deploy file integrity monitoring on sensitive system directories to detect unauthorized read attempts
• Use intrusion detection systems (IDS) with signatures for CWE-22 path traversal attacks

Monitoring Recommendations

• Enable verbose logging for the spire-pdf-mcp-server application to capture all filepath parameter values
• Set up alerts for requests containing encoded or double-encoded path traversal characters
• Monitor network traffic for unusual patterns of file access requests to the PDF server component
• Implement anomaly detection for file access patterns outside normal application behavior

How to Mitigate CVE-2026-7315

Immediate Actions Required

• Restrict network access to spire-pdf-mcp-server instances using firewall rules or network segmentation
• Implement input validation at the network perimeter using a WAF to filter path traversal attempts
• Review and audit file permissions to minimize the impact of potential unauthorized file access
• Consider temporarily disabling the vulnerable component until a patch is available

Patch Information

As of the last update on 2026-04-29, no official patch has been released by the project maintainers. The project was informed of the vulnerability through a GitHub issue but has not yet responded. Users should monitor the project repository for security updates and new releases addressing this vulnerability.

Workarounds

• Implement application-level input validation to reject filepath values containing ../, ..\, or encoded variants
• Configure a reverse proxy or WAF in front of the application to filter malicious requests
• Run the application with minimal filesystem permissions using principle of least privilege
• Isolate the spire-pdf-mcp-server in a container or chroot environment to limit filesystem access scope

# Example: Nginx configuration to block path traversal attempts
location /api/ {
    # Block common path traversal patterns
    if ($request_uri ~* "\.\.") {
        return 403;
    }
    if ($request_uri ~* "%2e%2e") {
        return 403;
    }
    proxy_pass http://localhost:8080;
}