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Revert "fix(core): escape overlapping comment delimiters in escapeCom… #69426

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Merged
kirjs merged 1 commit into from
Jun 18, 2026
Merged

Revert "fix(core): escape overlapping comment delimiters in escapeCom… #69426

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2 changes: 1 addition & 1 deletion packages/core/src/util/dom.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@
*
* see: https://html.spec.whatwg.org/multipage/syntax.html#comments
*/
const COMMENT_DISALLOWED = />|->|<!--|-->|--!>|<!-$/g;
const COMMENT_DISALLOWED = /^>|^->|<!--|-->|--!>|<!-$/g;
/**
* Delimiter in the disallowed strings which needs to be wrapped with zero with character.
*/
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31 changes: 3 additions & 28 deletions packages/core/test/util/dom_spec.ts
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Expand Up @@ -40,35 +40,10 @@ describe('comment node text escaping', () => {
expect(escapeCommentText('--!>')).toEqual('--!\u200b>\u200b');
expect(escapeCommentText('<!-')).toEqual('\u200b<\u200b!-');

// A standalone `>` or `->` is escaped regardless of position so that a delimiter which
// overlaps an earlier match (e.g. the `-->` in `<!-->`) can't survive a single pass.
expect(escapeCommentText('.>')).toEqual('.\u200b>\u200b');
expect(escapeCommentText('.->')).toEqual('.-\u200b>\u200b');
// Things which are OK
expect(escapeCommentText('.>')).toEqual('.>');
expect(escapeCommentText('.->')).toEqual('.->');
expect(escapeCommentText('<!-.')).toEqual('<!-.');
});

it('should escape delimiters that overlap an earlier match', () => {
// `<!-->` contains both `<!--` and a `-->` that shares its `--`; both must be neutralized.
expect(escapeCommentText('<!-->')).toEqual('\u200b<\u200b!--\u200b>\u200b');
expect(escapeCommentText('<!--!>')).toEqual('\u200b<\u200b!--!\u200b>\u200b');
expect(escapeCommentText('a<!-->b')).toEqual('a\u200b<\u200b!--\u200b>\u200bb');
});

it('should keep an injected payload inside a programmatically created comment', () => {
// `<!-->` closes a comment immediately (the `-->` overlaps the `<!--`), so without escaping
// the trailing markup leaks out of the comment and runs. Round-trip a comment node through
// serialization + re-parsing to confirm the payload stays inert comment text.
const host = document.createElement('div');
host.appendChild(
document.createComment(escapeCommentText('<!--><img src=x onerror="alert(1)">')),
);

const reparsed = document.createElement('div');
reparsed.innerHTML = host.innerHTML;

expect(reparsed.childNodes.length).toBe(1);
expect(reparsed.firstChild!.nodeType).toBe(Node.COMMENT_NODE);
expect(reparsed.getElementsByTagName('img').length).toBe(0);
});
});
});
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