Threats / Microsoft / CVE-2017-0263
CVE-2017-0263
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Win32k vulnerability
Microsoft Win32k privilege escalation vulnerability caused by improper memory object handling in the Windows kernel-mode driver. Use-after-free flaw enabling local attackers to escalate privileges.
Verdict
Today item — known-exploited.
A use-after-free vulnerability in Win32k allows local attackers to escalate privileges by exploiting improper memory object handling. The flaw has been actively exploited in the wild, posing significant risk to Windows systems requiring immediate patching.
CISA KEV Yes · 2022-02-104EPSS 0.10034 (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
12 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 2022-02-10).
Probability (EPSS)
EPSS 0.10034 — 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.
Weakness (CWE)
Mapped to CWE-416 Use After Free — 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 1735 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 execute code with limited user privileges on a target Windows system.
Business
An attacker gains initial access to the system through standard user account compromise or social engineering.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger the use-after-free condition in Win32k by manipulating kernel memory objects through the vulnerable driver interface.
Business
The system becomes unstable or crashes, but more critically, memory corruption occurs that can be controlled by the attacker.
3
Lateral reach — past segmentation narrative 3
Attacker
I leverage the memory corruption to execute arbitrary code in kernel context and escalate my privileges to SYSTEM level.
Business
The attacker gains complete control over the compromised system with the highest privilege level, enabling installation of malware, data theft, or lateral movement.
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