April 2026 Patch TuesdayKB5099539Out-of-band action

Microsoft · KB5099539

Linked CVE review

Deploy Microsoft Windows security update KB5099539

Linked CVEs
1
Confirmed exploited
1
PoC or lab evidence
0
Maximum CVSS
4.3
Evidence is kept separate

Confirmed exploitation, public exploit material, EPSS probability and CVSS severity answer different questions. “No confirmation recorded” means the checked sources do not currently confirm exploitation. It is not proof that exploitation has not occurred.

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1 of 1 linked CVEs shown
Confirmed exploitedCVSS above 9.0
CVE and descriptionSeverityExploit realityForecast and accessRemediation
CVE-2026-32202 Immediate evidence
Microsoft Windows Protection Mechanism Failure Vulnerability

Microsoft Windows Shell contains a protection mechanism failure vulnerability that allows an unauthorized attacker to perform spoofing over a network.

4.3 · CVSS 3.1 · MediumSource: CNAConfirmed in the wildCISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2026-04-28.None recordedNo exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.EPSS: 4.90% · 91.9th percentileForecast date: 2026-10-08NETWORK · LOW complexity · NONE privileges · REQUIRED user interactionPatch nowCISA confirms exploitation in the wild and lists 2026-05-12 as the remediation due date.Mitigation available. No fixed version is explicitly recorded in the structured CVE data.