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Date: Sun, 25 Sep 2011 11:02:17 +0200
From: Pierre Joye <>
To: Stas Malyshev <>
Cc: Vincent Danen <>, 
	"" <>, "" <>
Subject: Re: CVE request: is_a() function may allow arbitrary code execution
 in PHP 5.3.7/5.3.8

hi Stas,

I tend to disagree here. One of the CVE goal is not about declaring
one or the other guilty of bad practice(s) but about informing users
about security issues in the software they use and how to act
correctly to fix these issues.

The is_a change is typically one of these security issues. While being
a minor one (recommended ini settings or good code practices would
avoid it easily), it is still one. That's why I'd to go with assigning
one and link it to the bug.

On Sun, Sep 25, 2011 at 10:56 AM, Stas Malyshev <> wrote:

> Yes, it is a behavior change, and it shouldn't have happened in 5.3, the
> fact that it happened was a bad mistake, it is clear now.
> However, the security flaw is squarely in the code that a) misuses is_a b)
> doesn't have security checks and c) does not follow recommended best
> practices about PHP settings.
> As such, telling people that it was a flaw in PHP and that BC break reversal
> "fixed" it only gives them wrong ideas that their code was just fine. But in
> fact their code was broken and only by luck (and due to the haphazard way
> things were done in PHP where nobody bothered correlating function
> signatures with one another) in might have not been malfunctioning in this
> specific scenario. They need to fix that code ASAP, as they can not rely on
> luck anymore and they way is_a was changed is actually they way it should
> have worked from the start and the way is_subclass_of works right now.


@pierrejoye | |

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