Security readout for executives and security teams
Plain-English summary
A flaw in Microsoft Defender’s malware-scanning engine could let an unauthorized attacker run code after local access and user interaction. Successful exploitation could compromise data, alter systems, or disrupt availability. The supplied CVSS score is 7.8, rated high.
Executive priority
Treat as a high-priority endpoint remediation issue. Validate exposure promptly and deploy Microsoft’s approved update through normal emergency patch controls. Accelerate systems with greater local-user or untrusted-content exposure, while recognizing that active exploitation is not established by the supplied sources.
Technical view
CVE-2026-55012 is an integer overflow or wraparound vulnerability in Microsoft Malware Protection Engine, mapped to CWE-190 and CWE-122. The supplied vector indicates local attack access, low complexity, no privileges, required user interaction, unchanged scope, and high confidentiality, integrity, and availability impact.
Likely exposure
The bundle identifies Microsoft Malware Protection Engine version 1.1.0.0 as affected. Exposure depends on whether that engine version is installed and whether an attacker can obtain local access and induce required user interaction. No additional affected versions or products are established by the supplied evidence.
Exploitation context
The supplied record does not establish active exploitation, and the CVE is not marked as included in KEV. Exploitation requires a local attack path and user interaction but reportedly needs no existing privileges. Public exploit availability is not established by the bundle.
Researcher notes
The record links integer wraparound with possible heap memory corruption, but the bundle provides no detailed vulnerable component, trigger format, attack chain, or fixed version. Researchers should rely on Microsoft’s advisory for authoritative affected-version and remediation details. Absence from supplied KEV data does not prove exploitation has never occurred.
Mitigation direction
- Review Microsoft’s CVE advisory for the approved security update and deployment guidance.
- Update affected Microsoft Malware Protection Engine installations according to Microsoft guidance.
- Prioritize systems where untrusted users or files can reach Defender scanning workflows.
- Reduce unnecessary local access while remediation is pending.
Validation and detection
- Inventory Microsoft Malware Protection Engine versions across managed endpoints.
- Compare detected versions with Microsoft’s current affected and remediated version guidance.
- Confirm security intelligence and engine updates completed successfully on affected endpoints.
- Review endpoint telemetry for unusual code execution or crashes associated with Defender processes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-122: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-190: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-55012 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.85.9microsoftVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft Defender Remote Code Execution VulnerabilityCVE reference, microsoft · vendor-advisory, patch
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.