CVE-2026-55011
CVE-2026-55011 is a high-severity vulnerability in Microsoft Malware Protection Engine with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-191.
Key facts
- Severity: High (CVSS 3.x base score 7.8)
- EPSS exploit prediction: 0% (31st percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-191
- Affected product: Microsoft Malware Protection Engine
- Published:
- Last modified:
Description
Integer underflow (wrap or wraparound) in Microsoft Defender allows an unauthorized attacker to execute code locally.
Frequently asked questions
- What is CVE-2026-55011?
- Integer underflow (wrap or wraparound) in Microsoft Defender allows an unauthorized attacker to execute code locally.
- How severe is CVE-2026-55011?
- CVE-2026-55011 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-55011 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-55011?
- CVE-2026-55011 affects Microsoft Malware Protection Engine. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-55011?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2026-55011 published?
- CVE-2026-55011 was published on 2026-07-14 and last updated on 2026-07-24.
References
Affected products (1)
- cpe:2.3:a:microsoft:malware_protection_engine:*:*:*:*:*:*:*:*
More vulnerabilities in Microsoft Malware Protection Engine
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- CVE-2006-5270 — Critical (CVSS 9.3): Integer overflow in the Microsoft Malware Protection Engine (mpengine.dll), as used by Windows Live OneCare, Antigen,…
- CVE-2026-45584 — High (CVSS 8.1): Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network.
- CVE-2026-69414 — High (CVSS 7.8): Microsoft is aware of an elevation of privilege in the Microsoft Malware Protection Engine in Microsoft Defender…
- CVE-2026-55012 — High (CVSS 7.8): Integer overflow or wraparound in Microsoft Defender allows an unauthorized attacker to execute code locally.
- CVE-2026-50656 — High (CVSS 7.8): Microsoft is aware of an elevation of privilege in the Microsoft Malware Protection Engine in Microsoft Defender…
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Other CWE-191 (Integer Underflow) vulnerabilities
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- CVE-2026-51540 — Critical (CVSS 9.8): OpENer 2.3.0 (master branch up to commit 76b95cf) is vulnerable to a severe memory corruption issue caused by an…
- CVE-2026-53176 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: IB/isert: Reject login PDUs shorter than…
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