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HistoryAug 18, 2011 - 12:00 a.m.

ZDI-11-270: Mozilla Firefox SVGTextElement.getCharNumAtPosition Remote Code Execution Vulnerability






ZDI-11-270: Mozilla Firefox SVGTextElement.getCharNumAtPosition Remote Code Execution Vulnerability

August 17, 2011


7.5, (AV:N/AC:L/Au:N/C:P/I:P/A:P)

– Affected Vendors:

– Affected Products:
Mozilla Firefox

– TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability by Digital Vaccine protection filter ID 11213.
For further product information on the TippingPoint IPS, visit:

– Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code on
vulnerable installations of Mozilla Firefox. User interaction is
required to exploit this vulnerability in that the target must visit a
malicious page or open a malicious file.

The specific flaw exists within the code responsible for parsing SVG
text containers. The code within nsSVGGlyphFrame::GetCharNumAtPosition()
does not account for user defined getter methods modifying or destroying
the parent object. An attacker can abuse this flaw to create a dangling
pointer which is referenced during the traversal of the SVG container
hierarchy. This can be leveraged to execute arbitrary code within the
context of the browser.

– Vendor Response:
Mozilla has issued an update to correct this vulnerability. More
details can be found at:

– Disclosure Timeline:
2011-04-04 - Vulnerability reported to vendor
2011-08-17 - Coordinated public release of advisory

– Credit:
This vulnerability was discovered by:
* regenrecht

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