Affected: OpenClaw

OpenClaw versions prior to 2026.2.23 contain an html injection vulnerability in the HTML session exporter that allows attackers to execute arbitrary javascript by injecting malicious mimeType values in image content blocks. Attackers can craft session entries with specially crafted mimeType attributes that break out of the img src data-URL context to achieve cross-site scripting when exported HTML is opened.

Affected: npm: openclaw

## 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