Security readout for executives and security teams
Plain-English summary
A Microsoft Word flaw lets attacker-controlled input influence a security decision and bypass a protection. User interaction is required, but the attacker needs no prior privileges. Successful exploitation may seriously affect confidentiality, integrity, and availability. CISA’s Known Exploited Vulnerabilities listing makes this an urgent, real-world threat.
Executive priority
Treat remediation as immediate. Known exploitation, low attack complexity, and potentially high business impact outweigh the user-interaction requirement. Require rapid inventory, Microsoft update deployment, and documented exception handling for systems that cannot be promptly updated.
Technical view
CWE-807 describes reliance on untrusted inputs in a security decision. The CVSS 3.1 score is 7.8: local access, low complexity, no privileges, and required user interaction, with potentially high confidentiality, integrity, and availability impact. The source bundle does not identify the specific protection bypassed or resulting post-bypass behavior.
Likely exposure
Exposure exists where the listed Microsoft 365 Apps for Enterprise or Office LTSC 2021/2024 editions remain vulnerable, including the specified Mac editions. The supplied version values are broad and do not provide complete build ranges, so administrators must compare installed builds directly with Microsoft’s advisory.
Exploitation context
CISA KEV inclusion supports active exploitation. Available evidence indicates a local, low-complexity path requiring user interaction but no attacker privileges. The supplied sources do not describe observed campaigns, delivery methods, public proof-of-concept availability, exploitation scale, or the exact security feature being bypassed.
Researcher notes
The record establishes CWE-807, CVSS 7.8, affected product families, required user interaction, and KEV status. It does not disclose the trusted decision, bypass mechanism, exploitation artifacts, indicators, patch identifiers, or precise build boundaries. Avoid inferring code execution or a specific attack chain without additional vendor evidence.
Mitigation direction
- Review Microsoft’s CVE advisory for affected build details and applicable security updates.
- Deploy the Microsoft-provided update across affected Windows and Mac installations using normal change controls.
- Prioritize internet-facing, high-value, and frequently targeted user populations where affected Word editions are installed.
- Check Microsoft guidance for any temporary mitigations needed before update deployment completes.
Validation and detection
- Inventory Microsoft 365 Apps and Office LTSC editions across Windows and Mac endpoints.
- Compare installed editions and build numbers with Microsoft’s CVE advisory.
- Confirm applicable security updates installed successfully on every affected endpoint.
- Rescan endpoints and investigate update failures, unmanaged devices, and unsupported installations.
- Review security monitoring for activity associated with this CVE, while recognizing the bundle provides no indicators.
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-807: 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 lookupCVE-2026-21514 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
- Yes
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/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.
CISA KEV status
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:F/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:F/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.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2026-21514 added to CISA KEV
- 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
- 2026-02-10T00:00:00.000Z: CVE-2026-21514 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft Word Security Feature Bypass VulnerabilityCVE reference, microsoft · vendor-advisory, patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21514CVE reference, CISA-ADP · government-resource
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.
Reliance on Untrusted Inputs in a Security Decision
Reliance on Untrusted Inputs in a Security Decision represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.