September 2026 Patch TuesdayMSRC-2026-09-windows-update-informationNormal patch window

Microsoft · MSRC-2026-09-windows-update-information

Linked CVE review

Deploy Microsoft Windows update for HEVC Video Extensions, HEVC Video Extensions for Licensed Applications, HEVC Video Extensions from Device Manufacturer on Windows 10 Version 1809 for 32-bit Systems, plus 21 more

Linked CVEs: 2
Confirmed exploited: 0
PoC or lab evidence: 0
Maximum CVSS: 7.8

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.

2 of 2 linked CVEs shown

Confirmed exploitedCVSS above 9.0

CVE and description	Severity	Exploit reality	Forecast and access	Remediation
CVE-2026-58599 Scheduled assessment HEVC Video Extensions Remote Code Execution Vulnerability Heap-based buffer overflow in Microsoft Windows Codecs Library allows an unauthorized attacker to execute code locally.	7.8 · CVSS 3.1 · HighSource: CNA	No confirmation recordedNo CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.None recordedNo exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.	EPSS: 0.47% · 38.4th percentileForecast date: 2026-10-09LOCAL · LOW complexity · NONE privileges · REQUIRED user interaction	Within 7 daysHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.Patch available. An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
CVE-2026-58600 Scheduled assessment HEVC Video Extensions Elevation of Privilege Vulnerability Heap-based buffer overflow in Microsoft Windows Codecs Library allows an unauthorized attacker to elevate privileges locally.	7.8 · CVSS 3.1 · HighSource: CNA	No confirmation recordedNo CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.None recordedNo exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.	EPSS: 0.47% · 38.4th percentileForecast date: 2026-10-09LOCAL · LOW complexity · NONE privileges · REQUIRED user interaction	Within 7 daysHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.Patch available. An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.