CVE intelligence

CVE-2026-63540

Vulnerability intelligence

Published Nov 10, 2026Sources checked Nov 13, 2026

6.9MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2026-63540 and is rated Medium severity with a CVSS score of 6.9. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Nov 14, 2026

Release Notes

CISA KEVNot listedBased on the latest collected catalog

EPSS0.1%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-63540?

Heap-based buffer overflow for some Hyperscan before version v5.4.2.1 within Ring 3: User Applications may allow a denial of service. Unprivileged software adversary with an unauthenticated user combined with a low complexity attack may enable denial of service.

This result may potentially occur via local access when attack requirements are not present without special internal knowledge and requires passive user interaction. The potential vulnerability may impact the confidentiality (none), integrity (low) and availability (high) of the vulnerable system, resulting in subsequent system confidentiality (none), integrity (none) and availability (none) impacts.

Source: NVD