CVE-2006-1834 in Web Browser
Summary
by MITRE
Integer signedness error in Opera before 8.54 allows remote attackers to execute arbitrary code via long values in a stylesheet attribute, which pass a length check. NOTE: a sign extension problem makes the attack easier with shorter strings.
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Analysis
by VulDB Data Team • 06/22/2025
The vulnerability identified as CVE-2006-1834 represents a critical integer signedness error affecting Opera web browsers prior to version 8.54. This flaw resides in the browser's CSS parser implementation where improper handling of signed and unsigned integer values creates a condition that can be exploited by remote attackers to execute arbitrary code on affected systems. The vulnerability specifically manifests when processing stylesheet attributes containing unusually long values that bypass normal length validation checks through a mechanism involving integer overflow conditions.
The technical exploitation of this vulnerability leverages a sign extension problem that occurs during the parsing of CSS attributes. When Opera processes stylesheet data, it performs length checks on attribute values to prevent buffer overflows and other memory corruption issues. However, due to the signedness error, attackers can craft malicious CSS content with long values that appear to pass the length validation tests while actually causing integer underflow or overflow conditions. The sign extension aspect makes this attack vector particularly effective because shorter malicious strings can be crafted to exploit the vulnerability more easily than would otherwise be possible.
This vulnerability directly maps to CWE-190, which describes integer overflow and underflow conditions, and specifically relates to CWE-191, integer underflow, as the attack exploits the improper handling of signed integer values during length validation. The operational impact of this vulnerability extends beyond simple code execution to potentially allow full system compromise, as remote attackers can leverage this flaw to inject and execute arbitrary code within the context of the browser process. The attack requires no user interaction beyond visiting a malicious webpage containing the crafted CSS content, making it particularly dangerous in phishing scenarios or compromised websites.
From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.006 for command and scripting interpreter, specifically targeting the browser as a vector for code execution. The vulnerability demonstrates the importance of proper input validation and integer handling in web browser security contexts. The fact that shorter strings can be used to make the attack easier indicates that attackers can craft more efficient payloads that require less complexity to achieve successful exploitation. Organizations should consider implementing browser security updates as a priority, particularly for legacy Opera installations, while also deploying web application firewalls and content filtering solutions that can detect and block malicious CSS content before it reaches vulnerable browsers.