Fix stored XSS via BBCode attribute injection#58
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BBCode option values were substituted into HTML templates without escaping. A malformed option like [goal=x" onclick="alert(1)] triggered a ParserException fallback that preserved raw quotes, allowing attribute breakout and arbitrary event handler injection. Apply htmlspecialchars(ENT_QUOTES, UTF-8) to all option values before HTML substitution in CodeDefinition::asHtml(), and to the custom [code] tag's class attribute in Post::parse_content(). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
[goal=OPTION],[code=OPTION],[img=OPTION]) were inserted into HTML templates without escaping[goal=x" onclick="alert(1)]triggers aParserExceptionfallback in the option parser that preserves raw quotes, allowing HTML attribute breakout and arbitrary event handler injectionhtmlspecialchars(ENT_QUOTES, UTF-8)to all option values before HTML substitution inCodeDefinition::asHtml(), and to the custom[code]tag's class attribute inPost::parse_content()Affected tags
[goal=OPT]<div class="b_goal {option}">{option}— no validator[code=OPT]<code class="OPT">asHtml— no escaping[img=OPT]<img alt="{option}">{option}— no validatorTest plan
[goal=x" onclick="alert(1)]test[/goal]— verify alert does NOT fire on click[code=x" onmouseover="alert(1)]test[/code]— verify alert does NOT fire on hover[img=x" onerror="alert(1)]https://example.com/img.jpg[/img]— verify alert does NOT fire[goal=star]test[/goal]— verify normal usage still works[code=php]echo "hi";[/code]— verify code highlighting still works🤖 Generated with Claude Code