markup: restrict data URI scheme to safe image MIME types#8174
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The HTML sanitizer was configured to blanket-allow all data: URIs, which enabled stored XSS via data:text/html payloads in raw HTML anchor tags. Restrict the data: scheme to only allow safe image MIME types (png, jpeg, gif, webp, x-icon). Ref: GHSA-xrcr-gmf5-2r8j Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Feb 19, 2026
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
data:URL scheme in the HTML sanitizer to only allow safe image MIME types (png, jpeg, gif, webp, x-icon) instead of blanket-allowing all data URIs.Ref: GHSA-xrcr-gmf5-2r8j