Security readout for executives and security teams
Plain-English summary
A memory-safety flaw in Microsoft Excel can let an attacker run code with the victim’s permissions after required user interaction. Successful exploitation could expose, alter, or destroy data and disrupt the affected device. The listed affected products include several Microsoft Excel, Office, Microsoft 365, Mac LTSC, and Office Online Server editions.
Executive priority
Treat this as a high-priority patching issue because successful exploitation can fully compromise data and endpoint availability. Accelerate inventory and Microsoft update verification, especially for users handling external spreadsheets. Emergency incident response is not justified solely by this bundle because active exploitation is not established.
Technical view
CVE-2026-40362 is described as a use-after-free vulnerability enabling local code execution without prior privileges. CVSS 3.1 rates it 7.8: low complexity, user interaction required, unchanged scope, and high confidentiality, integrity, and availability impact. The bundle also assigns CWE-122, which does not precisely match the use-after-free description.
Likely exposure
Exposure is most likely where the specifically listed Microsoft 365 Apps, Excel 2016, Office 2019, Office LTSC, Mac LTSC, or Office Online Server products remain affected. The supplied version identifiers are broad and insufficient for reliable build-level determination; verify installed builds against Microsoft’s advisory.
Exploitation context
The CVSS vector indicates local attack access and required user interaction, with no privileges required. The bundle does not identify the required content or interaction. This CVE is not listed as KEV in the supplied evidence, and no cited source here establishes active exploitation or public exploit availability.
Researcher notes
The record describes a use-after-free, while the supplied CWE is CWE-122, a heap-based buffer overflow category; preserve this discrepancy when classifying root cause. The evidence establishes required user interaction and local code execution but provides no trigger format, affected build boundaries, exploit telemetry, or technical mitigation details.
Mitigation direction
- Review Microsoft’s CVE advisory for edition-specific security updates and installation requirements.
- Apply applicable Microsoft security updates to affected, supported products using normal change controls.
- Prioritize systems handling untrusted Office content or sensitive business data.
- Restrict untrusted Office content until updates are confirmed where operationally feasible.
Validation and detection
- Inventory the listed Microsoft Office, Excel, Microsoft 365, Mac LTSC, and Office Online Server products.
- Record exact installed builds rather than relying on the bundle’s broad version identifiers.
- Compare each build with Microsoft’s current CVE advisory and applicable security update guidance.
- Confirm update deployment through endpoint or server management records.
- Monitor security tooling for suspicious child processes or abnormal activity associated with Office applications.
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 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-2026-40362 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 Excel 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.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.