Re: CFD: eXIF 2017-0207

On Sun, Feb 12, 2017 at 7:46 PM, Glenn Randers-Pehrson
<[email protected]> wrote:
> Tomorrow I'll update the eXIf proposal with this:
>
> 135c135,139
> < This chunk does not introduce additional security issues.
> ---
>> The Exif specification does not contain a requirement that
>> tag "value offset" pointers actually point to a valid address
>> within the file (see Paragraph 4.6.2).  Although this seems to be
>> an implicit requrement, decoders should be prepared to encounter invalid
>> pointers and deal with them appropriately.

Indeed,  iCCP has the same issue.

FWIW, PNG does not have that issue; I believe it is inherently secure
in that regard.  The issue only arises with tags which have their own
structure and, at this point, I think that is only iCCP.

John Bowler

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