CVE-2015-6176

Vulnerability

Microsoft Edge's cross-site scripting (XSS) filter fails to properly handle HTML attributes in HTTP responses, allowing the filter to be bypassed. The vulnerability is addressed in MS15-125, which corrects how Microsoft Edge parses HTTP responses and prevents the XSS filter from incorrectly disabling HTML attributes [1]. Affected versions include Microsoft Edge on Windows 10 for 32-bit and x64-based systems prior to cumulative update 3116869 [1].

Exploitation

To exploit this vulnerability, an attacker must host a specially crafted webpage that, when viewed by a victim using an affected version of Microsoft Edge, delivers an HTTP response containing malicious HTML attributes that evade the XSS filter. The attacker does not require any special authentication or network position beyond being able to serve web content to the victim [1].

Impact

Successful exploitation allows the attacker to bypass the browser's XSS protection mechanism, enabling cross-site scripting attacks. The attacker can execute arbitrary script in the context of the current user and the target website, potentially leading to disclosure of sensitive information, session hijacking, or further compromise within the user's session [1].

Mitigation

Microsoft released security update MS15-125 (cumulative update 3116869) on December 8, 2015, which corrects the XSS filter behavior [1]. Users should apply the update via Windows Update or by manually installing the update. No workarounds are listed in the advisory. The vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog.