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Security Review Request for CSS Sizing Level 3

From: fantasai <fantasai.lists@inkedblade.net>
Date: Fri, 23 Oct 2020 16:37:12 -0700
To: public-web-security@w3.org
Cc: "www-style@w3.org" <www-style@w3.org>
Message-ID: <b4287c9e-716c-7678-808c-234375fb7388@inkedblade.net>
The CSSWG requests formal review of the CSS Sizing Module Level 3:

This CSS module defines the various sizing properties and concepts used 
throughout CSS. New features since CSS2 are summarized in

This specification is in the “almost CR” stage of development, so we expect it 
to transition, in more or less its current form, after completing horizontal 

The Privacy and Security Considerations section is here:

Please raise any issues in the csswg GitHub repo:
and let us know when you have completed your review.

= Self-Review Questionnaire: Security and Privacy =

2.1 What information might this feature expose to Web sites or other parties, 
and for what purposes is that exposure necessary?

In order to support automatic layout, CSS sizes boxes to fit their contents. 
In conjunction with various DOM and CSSOM APIs which can return the size of 
those boxes in JS, this can expose information about those contents. However, 
this information is more directly and easily available by inspecting the DOM 
for the contents, rather than indirecting through the parent's size. 
Containers that can't have their contents inspected (such as cross-origin 
iframes) also do not expose sizing information to the outer page, except 
insofar as replaced elements such as images expose their intrinsic size and/or 
aspect ratio.

2.2 Is this specification exposing the minimum amount of information necessary 
to power the feature?


2.3 How does this specification deal with personal information or 
personally-identifiable information or information derived thereof?

Not applicable

2.4 How does this specification deal with sensitive information?

Not applicable

2.5 Does this specification introduce new state for an origin that persists 
across browsing sessions?


2.6 What information from the underlying platform, e.g. configuration data, is 
exposed by this specification to an origin?


2.7 Does this specification allow an origin access to sensors on a user’s device


2.8 What data does this specification expose to an origin? Please also 
document what data is identical to data exposed by other features, in the same 
or different contexts.


2.9 Does this specification enable new script execution/loading mechanisms?


2.10 Does this specification allow an origin to access other devices?


2.11 Does this specification allow an origin some measure of control over a 
user agent’s native UI?


2.12 What temporary identifiers might this this specification create or expose 
to the web?


2.13 How does this specification distinguish between behavior in first-party 
and third-party contexts?

Not applicable

2.14 How does this specification work in the context of a user agent’s Private 
Browsing or "incognito" mode?

No difference

2.15 Does this specification have a "Security Considerations" and "Privacy 
Considerations" section?

Yes https://drafts.csswg.org/css-sizing-3/#priv-sec

2.16 Does this specification allow downgrading default security characteristics?


2.17 What should this questionnaire have asked?

Nothing springs to mind.

Received on Friday, 23 October 2020 23:37:27 UTC

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