OpenClaw Vulnerable to HTML injection via unvalidated image MIME type in data-URL interpolation

Summary

The HTML session exporter (src/auto-reply/reply/export-html/template.js) interpolates img.mimeType directly into <img src="data:..."> attributes without validation or escaping. A crafted mimeType value (e.g., x" onerror="alert(1)) can break out of the attribute context and execute arbitrary JavaScript.

Impact

An attacker who can control image entries in session data (via crafted tool results or session manipulation) can achieve XSS when the exported HTML is opened. The precondition is tighter than the main XSS finding (requires image content blocks with a malicious mimeType), but exploitation is straightforward.

Affected components

• src/auto-reply/reply/export-html/template.js — line 1032 (tool result images), line 1306 (user message images)

Reproduction

1. Craft a session entry with an image content block where mimeType is set to image/png" onerror="alert(document.domain)
2. Export the session to HTML
3. Open the exported HTML — the injected onerror fires

Remediation

• Added sanitizeImageMimeType() helper that validates mimeType against a whitelist of known image MIME types
• Falls back to application/octet-stream for unrecognized values, preventing attribute breakout

Fix

https://github.com/openclaw/openclaw/pull/24140