Threats / Microsoft / CVE-2020-1054
CVE-2020-1054
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Microsoft Win32k vulnerability
Microsoft Win32k privilege escalation vulnerability caused by improper memory object handling in the kernel-mode driver, enabling kernel-level code execution.
Verdict
Today item — known-exploited.
A kernel privilege escalation flaw in Win32k with high exploitability (EPSS 0.81) and confirmed active exploitation. Attackers can escalate from user mode to kernel mode, achieving complete system compromise.
CISA KEV Yes · 2021-11-035EPSS 0.54158 (verify live)6Exploit Public PoC7CVSS 73CISA SSVC Exploitation: active · Automatable: no · Impact: total4
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 0.54158 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C) · Affected: Microsoft, Win32k. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
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 531 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.
Public exploit available
Public exploit tooling is catalogued for this CVE (a functional/weaponized public exploit). Catalog entries: Metasploit module. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
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 target system with user-level privileges.
Business
An attacker establishes a foothold on the network with limited permissions.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I craft a malicious input that exploits the Win32k memory handling flaw to trigger kernel-mode code execution.
Business
The attacker escalates privileges to kernel level, bypassing security boundaries.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary code with kernel privileges to install persistent backdoors or disable security controls.
Business
The organization loses control of affected systems; attackers achieve persistent, undetectable access.
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
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by microsoftCNA
Credited with finding itNetanel Ben-Simon and Yoav Alon from Check Point Researchfinderbee13oy of Qihoo 360 Vulcan Teamfinder
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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