CVE-2015-2419
Microsoft Internet Explorer Memory Corruption Vulnerability
Description
CVE-2015-2419 is a critical memory corruption vulnerability (CWE-119) in the JScript9 scripting engine of Microsoft Internet Explorer that allows remote code execution when a user visits a specially crafted web page. The flaw occurs when JScript9 improperly handles objects in memory during JavaScript execution, allowing an attacker to corrupt memory and execute arbitrary code with the privileges of the current user. CISA has confirmed active exploitation and added CVE-2015-2419 to the Known Exploited Vulnerabilities catalog. With an EPSS score of 77.4% (99.9th percentile), this vulnerability is a high-priority threat for any system running affected versions of Internet Explorer.
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 | 10; 11 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- http://www.securitytracker.com/id/1032894(Broken Link, Third Party Advisory, VDB Entry)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-065(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2015-2419(US Government Resource)
Weakness Type
CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-119 describes a weakness where software performs operations on a memory buffer without properly restricting access to the intended boundaries, potentially leading to memory corruption, data disclosure, or code execution. In CVE-2015-2419, the JScript9 engine in Internet Explorer fails to properly manage memory boundaries during JavaScript processing, allowing an attacker to trigger a memory corruption condition that leads to arbitrary code execution.
Learn more: CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer
Impact Analysis
CVE-2015-2419 is remotely exploitable through a malicious web page, requiring no authentication and minimal user interaction beyond visiting the page. Successful exploitation grants the attacker code execution with the same privileges as the logged-in user, which on systems where users operate with administrative rights means full system control. Confidentiality, integrity, and availability are all fully compromised: the attacker can steal browser-stored credentials, install persistent malware, exfiltrate sensitive documents, and pivot to other network resources. The 99.9th percentile EPSS score indicates extremely high real-world exploitation activity, and this vulnerability has been widely integrated into exploit kits targeting Internet Explorer users.
Exploit Maturity
CVE-2015-2419 is confirmed as actively exploited in the wild by CISA and is listed in the Known Exploited Vulnerabilities catalog. This vulnerability was notably exposed as part of the Hacking Team data breach in July 2015, which included detailed exploit code and documentation. The EPSS score of 77.4% (99.9th percentile) reflects widespread exploitation activity. Following the Hacking Team leak, multiple exploit kits rapidly integrated CVE-2015-2419, making it a standard component of drive-by download campaigns.
Remediation
- Apply the Microsoft security update MS15-065 (July 2015) for Internet Explorer to address CVE-2015-2419 immediately.
- Migrate from Internet Explorer to a modern browser such as Microsoft Edge (Chromium), Google Chrome, or Mozilla Firefox, as Internet Explorer has reached end of life.
- If Internet Explorer must remain for legacy compatibility, restrict its use via Group Policy, disable JScript9 where possible, and ensure Enhanced Security Configuration is enabled on server systems.
- Deploy network-level protections such as web content filtering and IDS/IPS signatures to block known exploit kit delivery infrastructure.
- Conduct endpoint forensics on systems where Internet Explorer exploitation is suspected, focusing on indicators such as anomalous process spawning from iexplore.exe.
Technical Details
CVE-2015-2419 is a memory corruption vulnerability (CWE-119) in the JScript9 JavaScript engine (jscript9.dll) used by Microsoft Internet Explorer 10 and 11. The vulnerability is triggered when the JScript9 engine processes specially crafted JavaScript that causes incorrect handling of object properties during JIT compilation, leading to a use-after-free or type confusion condition in heap memory. An attacker can exploit this to gain read/write access to arbitrary memory locations within the Internet Explorer process, enabling bypass of ASLR through information leakage and construction of a ROP chain to circumvent DEP. The vulnerability was discovered in the Hacking Team breach data, which included a complete, working exploit with detailed comments explaining the exploitation methodology.
Frequently Asked Questions
Is CVE-2015-2419 being actively exploited?
Yes. CVE-2015-2419 is confirmed as actively exploited in the wild and is listed in the CISA KEV catalog. The vulnerability was exposed in the Hacking Team data breach in July 2015, and the EPSS score of 77.4% (99.9th percentile) reflects widespread exploitation activity.
What products are affected by CVE-2015-2419?
CVE-2015-2419 affects the JScript9 JavaScript engine in Microsoft Internet Explorer 10 and 11 across multiple Windows versions. Systems running modern browsers such as Microsoft Edge (Chromium) are not affected.
How do I fix CVE-2015-2419?
Apply the Microsoft security update MS15-065 (July 2015) for Internet Explorer. The most effective long-term solution is migrating to a modern browser, as Internet Explorer is no longer supported and will not receive future security updates.
How severe is CVE-2015-2419?
CVE-2015-2419 is rated CRITICAL and enables full remote code execution through a malicious web page. The 99.9th percentile EPSS score, its origin in the Hacking Team exploit arsenal, and CISA KEV listing confirm this is a high-severity, actively exploited vulnerability.
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