CVE-2018-8174: Microsoft Windows VBScript Engine Out-of-Bounds Write Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 15 Feb 2022, 1,378 days after the CVE record was published.

How likely is exploitation in the next 30 days?

88.2%

EPSS score, percentile 99.8 of all scored records

How severe?

7.5 High

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 15 Aug 2022. Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

• 32-bit Systems Service Pack 1
• x64-based Systems Service Pack 1
• (Server Core installation)
• Windows RT 8.1
• 32-bit Systems Service Pack 2
• 32-bit Systems Service Pack 2 (Server Core installation)

and 22 more in the table below

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 15 August 2022.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

• https://nvd.nist.gov/vuln/detail/CVE-2018-8174

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka "Windows VBScript Engine Remote Code Execution"

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2018-8174 to its Known Exploited Vulnerabilities (KEV) catalog on 15 Feb 2022.
• CISA marks it as known to be used in ransomware campaigns.
• The due date CISA sets for the required action is 15 Aug 2022.
• The CVE record was published on 9 May 2018, 1,378 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 7.5 (High), taken from CISA's enrichment of the record.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 88.2% (percentile 99.8), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka "Windows VBScript Engine Remote Code Execution Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-787: Out-of-bounds Write

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• 44741 (Exploit)
• 103998 (Vulnerability database)
• blog.0patch.com
• portal.msrc.microsoft.com

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