Threats / Microsoft / CVE-2019-0859
CVE-2019-0859
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Win32k vulnerability
Microsoft Win32k improperly handles memory objects, enabling privilege escalation to kernel mode execution. Actively exploited in the wild.
Verdict
Today item — known-exploited.
A memory handling flaw in Win32k permits local attackers to escalate privileges and execute arbitrary code with kernel-level access. Active exploitation demonstrates practical weaponization.
CISA KEV Yes · 2021-11-034EPSS 0.04151 (verify live)5Exploit Public PoC6CVSS 7.8 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
6 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 2021-11-03).
Probability (EPSS)
EPSS 0.04151 — 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 939 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 input that triggers improper object handling in Win32k.
Business
An attacker gains a foothold on the system through initial compromise or user interaction.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit the memory handling vulnerability to escalate my privileges from user mode to kernel mode.
Business
The attacker bypasses access controls and gains unrestricted system authority.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary code with kernel privileges to install persistence mechanisms or exfiltrate sensitive data.
Business
The organization loses confidentiality, integrity, and availability of critical systems and data.
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