Security readout for executives and security teams
Plain-English summary
This Microsoft Word flaw can let an attacker bypass a built-in security protection when a user interacts with a malicious or untrusted document. Microsoft rates it high severity, and CISA lists it as known exploited, so organizations using affected Office and Microsoft 365 builds should treat remediation as urgent.
Executive priority
High priority. This affects common business document workflows, requires user interaction, and has known exploitation evidence from CISA KEV. Prioritize patch deployment and exposure tracking.
Technical view
CVE-2026-21514 is a CWE-807 security feature bypass in Microsoft Office Word caused by relying on untrusted inputs in a security decision. CVSS 3.1 is 7.8 with local attack vector, low complexity, no privileges required, and user interaction required.
Likely exposure
Exposure is likely where affected Microsoft 365 Apps for Enterprise, Office LTSC 2021/2024, or Office LTSC for Mac 2021/2024 Word versions are installed and users open externally supplied documents.
Exploitation context
The source bundle marks the CVE as present in CISA KEV, which supports known exploitation. The provided sources do not describe exploit campaigns, affected file types, or weaponization details.
Researcher notes
Key details are AV:L, AC:L, PR:N, UI:R, S:U with high confidentiality, integrity, and availability impacts. The bundle does not provide exploit primitives, bypassed feature specifics, or detailed patch identifiers beyond the MSRC advisory.
Mitigation direction
- Apply the Microsoft security update referenced in the MSRC advisory.
- Prioritize remediation because CISA KEV indicates known exploitation.
- Check vendor guidance for any product-specific deployment notes.
- Reduce handling of untrusted Word documents until affected systems are updated.
Validation and detection
- Inventory Microsoft Word installations against the affected products and versions listed.
- Confirm deployed patch status against the MSRC CVE entry.
- Track remediation status for KEV-scoped assets separately.
- Verify users at highest phishing exposure are not running affected builds.
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.