Security readout for executives and security teams
Plain-English summary
A memory-safety flaw in listed Microsoft Office, Word, and Microsoft 365 products could let an unauthorized attacker run code on an affected computer. The CVSS score is 8.4 because successful exploitation could compromise confidentiality, integrity, and availability without privileges or user interaction. The supplied evidence does not establish active exploitation.
Executive priority
Treat this as a high-priority patching and exposure-validation issue. The potential business impact is complete compromise of an affected Office process and its accessible data. Accelerate remediation on sensitive and critical endpoints, while avoiding claims of an active campaign unless new authoritative evidence emerges.
Technical view
CVE-2026-40361 is a CWE-416 use-after-free vulnerability. Its CVSS 3.1 vector indicates a local, low-complexity attack requiring neither privileges nor user interaction, with high impact across confidentiality, integrity, and availability. The public bundle does not describe the trigger, attack chain, execution context, or reliable indicators of compromise.
Likely exposure
Exposure is limited to environments running the specifically listed Microsoft 365 Apps, Office 2019, Office LTSC 2021 or 2024, Office LTSC for Mac, or Word 2016 versions. Confirm exact affected builds against Microsoft’s advisory; the bundle provides only abbreviated version identifiers and no CPEs.
Exploitation context
The bundle marks this CVE as absent from KEV and supplies no cited evidence of active exploitation. CVSS records exploit maturity as unknown. A local attack vector does not mean low impact, but the available sources do not explain how an attacker obtains the required local attack path.
Researcher notes
The record identifies a use-after-free but lacks root-cause detail, trigger conditions, affected component boundaries, indicators, and exploitability analysis. The title names Outlook and Word, while the affected list includes broader Office products. Researchers should rely on Microsoft’s current advisory for precise build applicability and avoid inferring an email or document-based delivery mechanism.
Mitigation direction
- Review Microsoft’s CVE advisory and deploy the applicable security update through approved Office servicing channels.
- Prioritize affected endpoints handling sensitive information or supporting business-critical operations.
- Confirm exact product editions, platforms, and builds before concluding that systems are unaffected.
- If immediate updating is impossible, request Microsoft-supported mitigations and document the temporary risk decision.
Validation and detection
- Inventory installed Office products, editions, platforms, and build numbers across managed endpoints.
- Compare inventory results with Microsoft’s current affected-product and security-update tables.
- Verify the applicable update is installed successfully on each exposed endpoint.
- Rescan updated systems and investigate any remaining CVE-2026-40361 detections or update failures.
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-416: 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-2026-40361 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
- 8.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/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:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C2.55.9microsoftVulnerability scoring details
Base CVSS 3.1 score
8.4HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/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 Outlook and Word 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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.