CVE-2013-3893
Microsoft Internet Explorer Resource Management Errors Vulnerability
Description
CVE-2013-3893 is a high-severity use-after-free vulnerability in Microsoft Internet Explorer versions 6 through 11. The flaw exists in the SetMouseCapture implementation within mshtml.dll and allows remote attackers to execute arbitrary code through crafted JavaScript strings, as demonstrated by exploitation using ms-help: URLs that trigger loading of hxds.dll. With a CVSS v3.1 score of 8.8, this vulnerability was exploited in limited, targeted attacks before Microsoft released a patch. CISA has added CVE-2013-3893 to the Known Exploited Vulnerabilities catalog with a remediation deadline of September 2, 2025, and its EPSS score of 81.21% at the 99th percentile reflects one of the highest exploitation probabilities in the entire vulnerability database.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | internet explorer | 6; 7; 8; 9; 10; 11 |
References
- http://blogs.technet.com/b/srd/archive/2013/09/17/cve-2013-3893-fix-it-workaround-available.aspx(Exploit)
- http://blogs.technet.com/b/srd/archive/2013/10/08/ms13-080-addresses-two-vulnerabilities-under-limited-targeted-attacks.aspx(Vendor Advisory)
- http://jvn.jp/en/jp/JVN27443259/index.html(Third Party Advisory)
- http://jvndb.jvn.jp/ja/contents/2013/JVNDB-2013-000093.html(Third Party Advisory)
- http://packetstormsecurity.com/files/162585/Microsoft-Internet-Explorer-8-SetMouseCapture-Use-After-Free.html(Exploit)
- http://pastebin.com/raw.php?i=Hx1L5gu6(Exploit)
- http://technet.microsoft.com/security/advisory/2887505(Vendor Advisory)
- http://www.securityfocus.com/bid/62453(Broken Link)
- http://www.us-cert.gov/ncas/alerts/TA13-288A(US Government Resource)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-080(Vendor Advisory)
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18665(Broken Link)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3893(US Government Resource)
Weakness Type
CWE-416: Use After Free
CVE-2013-3893 is classified under CWE-416 (Use After Free), a memory corruption vulnerability where software accesses a memory pointer after the referenced memory has been freed. In Internet Explorer's mshtml.dll, the SetMouseCapture function continues to reference a DOM object after it has been deallocated during JavaScript execution, allowing an attacker to manipulate heap memory to achieve code execution.
Learn more: CWE-416 — Use After Free
CWE-399: Resource Management Errors
This vulnerability is also associated with CWE-399 (Resource Management Errors), a broader category encompassing improper management of system resources including memory. The underlying issue in Internet Explorer is a failure to properly track the lifecycle of DOM objects referenced by the mouse capture subsystem.
Learn more: CWE-399 — Resource Management Errors
Impact Analysis
CVE-2013-3893 poses severe risk due to Internet Explorer's historical dominance as a web browser. The vulnerability is network-exploitable (AV:N) with low attack complexity (AC:L), requires no authentication (PR:N), and needs only user interaction (UI:R) in the form of visiting a malicious webpage. Confidentiality (High): successful exploitation grants the attacker full access to data within the browser process and the user's session, including cookies, saved passwords, and browsing data. Integrity (High): the attacker can execute arbitrary code with the user's privileges, install malware, modify files, and establish persistent access. Availability (High): the compromised system can be rendered unusable through malware deployment or resource exhaustion. The EPSS score of 81.21% at the 99th percentile places this among the most exploited vulnerabilities ever recorded. The attack was demonstrated using ms-help: protocol handlers to load hxds.dll, providing a reliable exploitation technique that bypasses some browser security mechanisms.
Exploit Maturity
CVE-2013-3893 has an extremely mature exploit landscape. Public exploit code is available via Microsoft SRD blog and a proof-of-concept on Pastebin, and a full Metasploit module is available via Packet Storm Security. Microsoft confirmed limited targeted attacks exploiting this vulnerability before releasing MS13-080. CISA has confirmed active exploitation through KEV catalog inclusion. The EPSS score of 81.21% at the 99th percentile indicates near-certain exploitation, placing it in the top 1% of all known vulnerabilities. The vulnerability was addressed in Microsoft Security Advisory 2887505 and subsequently patched in MS13-080.
Remediation
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Apply Microsoft Security Bulletin MS13-080 which addresses CVE-2013-3893 along with other Internet Explorer vulnerabilities. The bulletin is available at MS13-080.
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Migrate away from Internet Explorer entirely. All versions of Internet Explorer (6 through 11) are affected and the browser has reached end of life. Microsoft recommends migrating to Microsoft Edge. Organizations still running IE should prioritize browser migration as a critical security initiative.
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Disable the ms-help: protocol handler as an interim mitigation if Internet Explorer must remain in use. The exploit chain demonstrated in the wild leveraged ms-help: URLs to load hxds.dll, and blocking this protocol handler disrupts the known attack vector.
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Implement network-level protections including web content filtering and intrusion detection signatures for known CVE-2013-3893 exploit patterns. Deploy browser isolation solutions to sandbox web browsing activity and prevent exploitation from reaching the endpoint.
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Audit the environment for systems still running Internet Explorer as a default browser, including legacy web applications that require IE compatibility. Consider using IE mode in Microsoft Edge for legacy application support rather than maintaining standalone IE installations.
Technical Details
CVE-2013-3893 is a use-after-free vulnerability in the SetMouseCapture implementation within Internet Explorer's mshtml.dll. The CVSS v3.1 vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H reflects network-based exploitation requiring only that a user visit a malicious webpage. The vulnerability occurs when crafted JavaScript manipulates DOM elements in a way that causes the SetMouseCapture function to retain a reference to an object that has been freed from memory. When this dangling pointer is subsequently dereferenced, the application accesses memory that may have been reallocated for other purposes. Attackers leverage heap spraying and precise memory layout manipulation to place controlled data at the freed location, enabling control over execution flow when the stale pointer is used. The demonstrated exploitation technique uses ms-help: URLs to trigger loading of hxds.dll, which provides additional gadgets for achieving reliable code execution. All Internet Explorer versions from 6 through 11 are affected, and the dual CWE classification under CWE-416 (Use After Free) and CWE-399 (Resource Management Errors) reflects both the specific vulnerability mechanism and the broader resource lifecycle management failure.
Frequently Asked Questions
Is CVE-2013-3893 being actively exploited?
Yes. CVE-2013-3893 was used in targeted attacks before Microsoft released a patch, and public exploit code including Metasploit modules is widely available. CISA has confirmed active exploitation, and the EPSS score of 81.21% at the 99th percentile indicates near-certain exploitation activity.
What products are affected by CVE-2013-3893?
Microsoft Internet Explorer versions 6, 7, 8, 9, 10, and 11 are all affected. The vulnerability exists in the mshtml.dll component shared across all IE versions.
How do I fix CVE-2013-3893?
Apply Microsoft Security Bulletin MS13-080 or, preferably, migrate to Microsoft Edge. Internet Explorer has reached end of life and should be replaced entirely. As an interim measure, disable the ms-help: protocol handler.
How severe is CVE-2013-3893?
CVE-2013-3893 has a CVSS v3.1 score of 8.8 (High severity) and an EPSS score at the 99th percentile, making it one of the most exploited vulnerabilities ever documented. It enables remote code execution through malicious web pages.
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