Fix XSS in semantic HTML export: escape code-block language#4818
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LeeSeungjae00 wants to merge 1 commit into
Open
Fix XSS in semantic HTML export: escape code-block language#4818LeeSeungjae00 wants to merge 1 commit into
LeeSeungjae00 wants to merge 1 commit into
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The language value was interpolated into the data-language attribute without escaping, allowing XSS via getSemanticHTML(). Fixes slab#4789
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Review (via AI-assisted code review): APPROVE This is a correct, minimal fix for a real XSS vector.
Notes (non-blocking): this overlaps with #4774 (which contains the identical one-line syntax fix plus broader changes) and #4788 — whichever lands first, the others should rebase and drop the duplicate hunk. No CI runs have executed on this fork head, so please trigger the unit suite before merge. |
This was referenced Jul 23, 2026
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Summary
Fixes #4789.
SyntaxCodeBlockContainer.html()interpolates the code block's language value into thedata-languageattribute without escaping, while the code content itself goes throughescapeText(). The language can be set to an arbitrary string viaformatLine(0, 1, 'code-block', value)(or crafted pasted content), so a value like"><img src=x onerror="alert(1)">breaks out of the attribute and executes script wherever the output ofgetSemanticHTML()is rendered.This is the remaining code path not covered by #4774, which fixes the same pattern in the formula and video formats. Related advisory: GHSA-v3m3-f69x-jf25 (CVE-2025-15056).
Fix
Wrap the language value with the existing
escapeText()helper — the same one-line pattern already used for the code content on the next line.Testing
<imgpayload present in the output; with the fix it passes.🤖 Generated with Claude Code