CVE-2026-7182: Diagram Export Path Traversal Vulnerability

CVE-2026-7182 Overview

CVE-2026-7182 is a path traversal vulnerability in the DHTMLX Diagram export module. The export module fails to sanitize HTML input passed to the src attribute. An unauthenticated attacker can craft an HTML payload that references local files on the server. The export pipeline then includes those files in the generated PDF, exposing their contents to the requester.

The issue is tracked as CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The vendor fixed the flaw in Diagram version 1.1.1.

Critical Impact

Unauthenticated attackers can read arbitrary local files from servers running vulnerable DHTMLX Diagram versions by abusing the PDF export functionality.

Affected Products

• DHTMLX Diagram export module versions prior to 1.1.1
• Applications embedding DHTMLX Diagram for server-side PDF export
• Web services exposing diagram export endpoints without authentication

Discovery Timeline

• 2026-05-15 - CVE-2026-7182 published to NVD
• 2026-05-15 - Last updated in NVD database

Technical Details for CVE-2026-7182

Vulnerability Analysis

The DHTMLX Diagram export module accepts HTML content and renders it into a PDF document. During rendering, the module resolves resources referenced through HTML attributes such as src on <img> or similar tags. The module does not sanitize these attributes against local filesystem paths or restricted URI schemes.

An attacker submits HTML containing a src attribute that points to a local file path on the server. The renderer dereferences that path, reads the file contents, and embeds the data into the resulting PDF. The PDF is then returned to the unauthenticated caller, completing the information disclosure.

Server-side files such as configuration files, credentials, source code, and operating system files become readable through this channel. The vulnerability is exploitable over the network without privileges or user interaction.

Root Cause

The root cause is missing HTML sanitization in the export pipeline. The module trusts attacker-supplied attribute values when resolving external resources. There is no allowlist of permitted URI schemes, no path normalization to block traversal sequences, and no isolation of file system access during PDF generation.

Attack Vector

Exploitation requires the attacker to send a single HTTP request containing crafted HTML to an endpoint that invokes the diagram export function. The HTML payload uses a src attribute targeting a sensitive local path. The server processes the request, renders the file into the PDF, and returns the document. No authentication, prior access, or social engineering is required. Refer to the CERT Polska advisory for CVE-2026-7182 for additional technical context.

Detection Methods for CVE-2026-7182

Indicators of Compromise

• HTTP requests to diagram export endpoints containing src attributes with absolute file paths, file:// URIs, or ../ traversal sequences.
• Generated PDF artifacts containing rendered contents of server configuration files, /etc/passwd, application source, or other non-diagram data.
• Unexpected file read access events on the application server originating from the PDF rendering process.

Detection Strategies

• Inspect application logs for export requests whose HTML payloads include suspicious schemes (file:, php:, expect:) or path traversal patterns in src values.
• Monitor outbound responses from the export endpoint for PDFs that exceed normal size baselines or are produced from short, anomalous input payloads.
• Correlate process telemetry on the rendering host to identify the PDF generator opening files outside expected resource directories.

Monitoring Recommendations

• Enable verbose request logging on the export endpoint and retain payload bodies for forensic review.
• Alert on rendering process file opens that touch paths under /etc, /root, application secret directories, or user home directories.
• Track frequency of export requests from individual source IPs to detect enumeration of file paths.

How to Mitigate CVE-2026-7182

Immediate Actions Required

• Upgrade the DHTMLX Diagram export module to version 1.1.1 or later, which contains the vendor fix.
• Place the export endpoint behind authentication and rate limiting until the patched version is deployed.
• Audit recent export logs for crafted src values and rotate any credentials present in files that may have been disclosed.

Patch Information

The vendor resolved the issue in DHTMLX Diagram version 1.1.1 by introducing HTML sanitization on the src attribute in the export module. Review the DHTMLX Diagram release notes and the DHTMLX Diagram product documentation for upgrade guidance.

Workarounds

• Strip or reject src, href, and other resource-referencing attributes in HTML input before passing it to the export module.
• Run the PDF rendering process under a dedicated low-privilege account with filesystem access restricted to the diagram resource directory.
• Deploy a web application firewall rule that blocks export payloads containing file://, absolute paths, or ../ sequences.

# Example WAF pattern to block traversal payloads in export requests
# Reject requests where the body contains a src attribute referencing local files
SecRule REQUEST_URI "@beginsWith /diagram/export" \
    "id:1007182,phase:2,deny,status:400,\
    chain,msg:'CVE-2026-7182 path traversal attempt'"
    SecRule REQUEST_BODY "@rx (?i)src\s*=\s*[\"'](file:|/|\\\\|\.\./)"