Internet Explorer CVE-2011-1255

Successful exploitation requires the victim to use Microsoft Internet Explorer versions 6, 7, or 8 specifically - Internet Explorer 9 and later are not vulnerable due to re-architected HTML+TIME implementation. The attack requires user interaction (UI:R implied by AC:M) to visit a malicious webpage or open a crafted HTML document that contains specially designed HTML+TIME elements. No authentication is required (PR:N) as the vulnerability can be triggered against any user browsing to attacker-controlled content. The HTML+TIME feature must be enabled, which is the default configuration in IE 6-8. Exploitation complexity is medium (AC:M), suggesting reliable exploitation requires precision in memory layout manipulation and timing to successfully trigger the uninitialized or freed object access. Modern exploit mitigation technologies such as DEP (Data Execution Prevention) and ASLR (Address Space Layout Randomization) on newer Windows versions may increase exploitation difficulty but do not prevent exploitation entirely on IE 6-8.

This vulnerability presents significant real-world risk based on converging threat intelligence signals. The CVSS score of 9.3 reflects network-based attack delivery (AV:N) with medium complexity (AC:M) requiring user interaction to visit a malicious page, but resulting in complete system compromise (C:C/I:C/A:C). The EPSS score of 52.37% places this in the 98th percentile for exploitation probability, indicating over half of similar vulnerabilities are exploited in practice. Public exploit code availability (Exploit-DB ID 20547) significantly lowers the barrier for exploitation. However, several factors moderate immediate risk: the vulnerability is over a decade old with vendor patches available since MS11-050 (June 2011), affected IE versions 6-8 represent legacy browsers with diminishing market share, and the attack requires user interaction to view malicious web content. The medium attack complexity (AC:M) suggests exploitation requires some precision in crafting the malicious HTML+TIME elements. Organizations still running IE 6-8 in 2025 face critical risk as these browsers lack modern security mitigations and are no longer supported, making this a viable attack vector for targeted campaigns against legacy enterprise environments.

An attacker hosts a malicious webpage containing specially crafted HTML+TIME elements designed to trigger uninitialized memory access or use-after-free conditions in Internet Explorer's rendering engine. When a user running IE 6, 7, or 8 visits the page through phishing emails, malicious advertisements, or compromised legitimate websites, the browser processes the TIME elements and accesses the corrupted memory object, allowing the attacker to execute arbitrary code with the user's privileges and install malware or establish persistent access.