Threats / Microsoft / CVE-2018-8589
CVE-2018-8589
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Win32k vulnerability
Windows Win32k.sys improperly handles calls, allowing privilege escalation to SYSTEM context. Actively exploited in the wild.
Verdict
Today item — known-exploited.
A local privilege escalation flaw in Win32k.sys enables attackers to execute code with SYSTEM privileges. Active exploitation in the wild increases risk despite moderate EPSS score.
CISA KEV Yes · 2022-05-234EPSS 0.03023 (verify live)5CVSS 7.8 (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 2022-05-23).
Probability (EPSS)
EPSS 0.03023 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) · Affected: Microsoft, Win32k. 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.
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 1286 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 gain initial access to a Windows system with limited user privileges.
Business
An attacker establishes a foothold on the network with user-level access.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I craft a malicious call to Win32k.sys to trigger the privilege escalation vulnerability.
Business
The vulnerability is weaponized through targeted exploitation techniques.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary code in the SYSTEM security context after successful exploitation.
Business
The attacker achieves complete system compromise with highest privileges.
4
Data at risk — exfiltration narrative 4
Attacker
I maintain persistence and move laterally across the network from the compromised system.
Business
Enterprise infrastructure becomes vulnerable to widespread compromise and data exfiltration.
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