Vulnerability record

CVE-2018-8373

Microsoft Scripting Engine Memory Corruption Vulnerability

HighExploitation confirmedCISA KEV

What should I do?

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Internet Explorer Scripting Engine, fix it now.

CISA required action: Apply updates per vendor instructions.

US federal civilian agencies must remediate by Apr 15, 2022.

Patch status

Official fix available since Sep 30, 2026

Apply the vendor's update to every affected system. Check the fixed-in versions below where known.

Basis: NVD patch reference

Patch or advisory on portal.msrc.microsoft.com (opens in a new tab)

Description

A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Internet Explorer, aka "Scripting Engine Memory Corruption Vulnerability." This affects Internet Explorer 9, Internet Explorer 11, Internet Explorer 10. This CVE ID is unique from CVE-2018-8353, CVE-2018-8355, CVE-2018-8359, CVE-2018-8371, CVE-2018-8372, CVE-2018-8385, CVE-2018-8389, CVE-2018-8390.

Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.

Affected products

Products affected by this vulnerability, with versions and the source of each entry
Product	Vendor	Affected versions	Source
Internet Explorer	Microsoft	11; 10; 9	NVD
Internet Explorer Scripting Engine	Microsoft	—	KEV

Sources: NVD = NIST National Vulnerability Database; KEV = CISA Known Exploited Vulnerabilities catalog.

Intelligence timeline

Developments from the last 30 days, newest first.

CVSS scoredUpdateKEVSep 30, 2026
CVE-2018-8373 scored CVSS 7.5: Microsoft Internet Explorer Scripting Engine, Microsoft Scripting Engine Memory Corruption Vulnerability
CISA lists this as exploited in the wild. Unpatched Internet Explorer Scripting Engine systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch releasedUpdateKEVSep 30, 2026
Patch released for CVE-2018-8373: Microsoft Internet Explorer Scripting Engine, Microsoft Scripting Engine Memory Corruption Vulnerability
An official fix is now available for Microsoft Internet Explorer Scripting Engine. This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference

1 earlier event is available with a subscription. See plans.

Coverage

We have not published a story about this vulnerability yet.

References

nvd.nist.gov https://nvd.nist.gov/vuln/detail/CVE-2018-8373
securityfocus.com http://www.securityfocus.com/bid/105037
securitytracker.com http://www.securitytracker.com/id/1041483
portal.msrc.microsoft.com https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8373
cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-8373