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safe_mode replaces unsafe link hrefs with '#', but image src values were passed through unchecked, so  produced an img tag with a javascript: src. Apply the same _safe_href check in LinkProcessor.process_image. Base64 image data URLs stay allowed, but only with a plain base64 payload, so a code span can't break out of the src attribute. Fixes trentm#764 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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In safe mode, links whose URL fails
_safe_hrefgethref="#", but image sources were never checked, so)rendered<img src="javascript:alert(1)">.process_imagenow runs the same check and falls back to#, like links do. Base64data:image/...URLs still work sincedata_urls_in_safe_moderelies on them, but only when the payload is plain base64: before, a code span in one could break out ofsrc(![](data:image/png;base64,x" onerror="alert(1)//)). Anything links already reject now givessrc="#"too, including otherdata:URLs, URLs with spaces or', and an empty![alt](), so I updated thesrcvalues in four existing XSS fixtures and addedimage_safe_urls.Fixes #764