Is CVE-2026-55011 in the CISA KEV catalog?

No. CVE-2026-55011 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-55011?

CVE-2026-55011 has a CVSS v3 base score of 7.8 (HIGH).

How do I fix or mitigate CVE-2026-55011?

No published fix for CVE-2026-55011 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-55011

HIGH

7.8

CVSS v3

NVD

Description

Integer underflow (wrap or wraparound) in Microsoft Defender allows an unauthorized attacker to execute code locally.

CWE-191

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploit Intelligence

EPSS data unavailable for this CVE.

References

Other references1

msrc.microsoft.com

Related Vulnerabilities

Other CWE-191 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0497	Critical	9.8	100%	KEV	Fix
CVE-2020-36221	High	7.5	84%	-	Fix
CVE-2020-36228	High	7.5	83%	-	Fix
CVE-2023-31102	High	7.8	71%	-	Fix
CVE-2024-38063	Critical	9.8	71%	-	Fix
CVE-2017-14496	High	7.5	66%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-14.