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Category:   Application (Web Browser)  >   Opera Vendors:   Opera Software
Opera Large Link Address Heap Overflow Lets Remote Users Execute Arbitrary Code
SecurityTracker Alert ID:  1017080
SecurityTracker URL:
CVE Reference:   CVE-2006-4819   (Links to External Site)
Date:  Oct 18 2006
Impact:   Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 9.x prior to 9.02
Description:   iDEFENSE reported a vulnerability in Opera. A remote user can cause arbitrary code to be executed on the target user's system.

A remote user can create a specially crafted URL that, when loaded by the target user (or loaded via HTML tags), will trigger a heap overflow and execute arbitrary code on the target system. The code will run with the privileges of the target user.

The vendor was notified on September 15, 2006.

Impact:   A remote user can create a URL that, when loaded by the target user, will execute arbitrary code on the target user's system.
Solution:   The vendor has issued a fixed version (9.02).

The Opera advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Boundary error
Underlying OS:  Linux (Any), Windows (Any)

Message History:   None.

 Source Message Contents

Subject:  iDefense Security Advisory 10.17.06: Opera Software Opera Web Browser

Opera Software Opera Web Browser URL Parsing Heap Overflow Vulnerability

iDefense Security Advisory 10.17.06
Oct 17, 2006


Opera is a cross-platform web browser. More information is available


Remote exploitation of a heap overflow vulnerability within version 9 of
Opera Software's Opera Web browser could allow an attacker to execute
arbitrary code on the affected host.

A flaw exists within Opera when parsing a tag that contains a URL. A
heap buffer with a constant size of 256 bytes is allocated to store the
URL, and the tag's URL is copied into this buffer without sufficient
bounds checking of its length. The vulnerable code would look something
like this in C/C++:

char *local_url = malloc(256);

strcpy(local_url, tag_url);

This URL can be inserted into any tag, such as an iframe.  The range of
characters that can be used to overflow the buffer is limited.


Successful remote exploitation allows an attacker to execute arbitrary
code with the privileges of the logged in user.  A failed exploitation
attempt may result in the browser crashing.  The attacker would first
need to construct a website containing the malicious tag and trick the
vulnerable user into visiting the site. This would trigger the
vulnerability and allow the code to execute with the privileges of the
local user.

The range of characters available does not make this vulnerability
significantly more difficult to exploit.  Through the use of JavaScript
or large compressed image files the attacker can have nearly complete
control of the heap.


iDefense Labs has confirmed Opera versions 9.0 and 9.01 on both Windows
and Linux are vulnerable. Version 8 is not vulnerable.


iDefense is currently unaware of any effective workarounds for this


Opera has addressed this vulnerability with version 9.02 of the Opera
Web Browser.  More information can be found in Opera's advisory at


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-4819 to this issue. This is a candidate for inclusion in
the CVE list (, which standardizes names for
security problems.


09/15/2006  Initial vendor notification
09/29/2006  Initial vendor response
10/17/2006  Coordinated public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Permission is granted for the redistribution of this alert
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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.

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