CVE-2013-3893: Microsoft Internet Explorer mshtml SetMouseCapture use-after-free

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 17 September 2026. Confidence: high.

critical priorityThe flaw is remotely exploitable, has known public exploits, is in CISA KEV, and has a very high EPSS score, making it an urgent patching priority.

What it is

A use-after-free flaw exists in the SetMouseCapture implementation in mshtml.dll in Internet Explorer 6 through 11. Crafted JavaScript strings, including via an ms-help: URL that loads hxds.dll, can trigger the bug and allow remote code execution. The issue is remotely reachable and has been exploited in targeted attacks.

Impact

An attacker can execute arbitrary code in the context of the affected browser process, giving full control of the user's session. Successful exploitation can lead to data theft, installation of malware, or further lateral movement.

Attack surface

Reached over the network by a victim visiting a crafted web page or opening a malicious link; the CVSS vector shows no privileges required but user interaction is required. No authentication is needed.

Exploitation

The vulnerability is listed in CISA KEV (added 2025-08-12) and has a very high EPSS probability (0.8593, 99.7th percentile). Multiple references are tagged as Exploit, and vendor advisories note limited targeted attacks.

What to do

• Apply the Microsoft security update MS13-080 or later cumulative updates for Internet Explorer.
• If patching is not immediately possible, apply the vendor Fix it workaround described in Microsoft Security Advisory 2887505.
• Discontinue use of Internet Explorer 6 through 11 and migrate to a supported browser.
• Block or restrict ms-help: URL handling and hxds.dll loading where feasible.
• Follow BOD 22-01 guidance for cloud services and prioritize remediation per KEV due date.

Detection

• Monitor for processes loading hxds.dll or handling ms-help: URLs unexpectedly.
• Hunt for Internet Explorer crashes or abnormal child process creation following browsing activity.
• Review proxy and web logs for known exploit delivery patterns or malicious JavaScript strings targeting SetMouseCapture.
• Use endpoint detection to flag use-after-free exploitation behavior in mshtml.dll, such as suspicious memory operations in IE processes.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.