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Re: [csswg-drafts] [selectors] :link and :visited are not mutually exclusive in implementations

From: Emilio Cobos Álvarez via GitHub <sysbot+gh@w3.org>
Date: Wed, 06 Dec 2017 00:50:10 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-349492242-1512521406-sysbot+gh@w3.org>
> Apply all :link rules and, for allowed properties, also apply all :visited rules (at the same time).

As I understand it, assuming you only apply `:visited` rules to actually visited links (which per your description looks like it), your behavior can be prone to timing attacks.

At least Gecko cascades and selector-matches both visited and unvisited rules _regardless_ of whether the link was actually visited in the first place, to prevent this kind of issues. If I'm not wrong, I should be able to query history in edge adding very expensive selectors to the `:visited` rules, and observing the time difference it takes to style a link vs another.

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Received on Wednesday, 6 December 2017 00:50:12 UTC

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