Threats / Microsoft / CVE-2018-8373
CVE-2018-8373
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Internet Explorer Scripting Engine vulnerability
A remote code execution vulnerability in Internet Explorer's scripting engine allows attackers to execute arbitrary code by exploiting improper memory object handling.
Verdict
Today item — known-exploited.
This vulnerability enables unauthenticated remote code execution through specially crafted web content. Active exploitation in the wild and high EPSS score indicate significant risk to unpatched systems.
CISA KEV Yes · 2022-03-254EPSS 0.54457 (verify live)5CVSS 7.5 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
5 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-25).
Probability (EPSS)
EPSS 0.54457 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H) · Affected: Microsoft, Internet Explorer Scripting Engine. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 1318 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious webpage or email containing specially formatted script that triggers improper memory handling in the scripting engine.
Business
Users visiting untrusted websites or opening malicious email content face immediate system compromise without additional user interaction beyond browsing.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger a memory corruption condition that allows me to execute arbitrary code with the privileges of the Internet Explorer process.
Business
Attackers gain code execution capability to steal credentials, install malware, or pivot to internal networks from compromised endpoints.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistence or deploy secondary payloads to maintain access and expand my foothold across the target environment.
Business
Organizations face data exfiltration, ransomware deployment, or long-term compromise of critical systems and intellectual property.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05