Security readout for executives and security teams
Plain-English summary
This is a high-severity Microsoft Access remote code execution vulnerability. A user interaction is required, so business risk is highest where staff open Access or Office files from untrusted sources. Microsoft lists official remediation, and the source bundle does not show active exploitation.
Executive priority
Treat as a priority endpoint patching item, especially for teams that process external documents. The issue has high impact but needs user interaction and has no supplied evidence of active exploitation.
Technical view
CVE-2025-21186 affects Microsoft Access and Office-family products and is mapped to CWE-122, a heap-based buffer overflow. CVSS 3.1 is 7.8 with local attack vector, low complexity, no privileges required, required user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely on endpoints running affected Microsoft 365 Apps for Enterprise, Microsoft Access 2016, Office 2019, Office LTSC 2021, or Office LTSC 2024 versions listed by Microsoft.
Exploitation context
The provided data marks this as not in CISA KEV and CVSS exploit maturity as unproven. There is no cited evidence of active exploitation in the supplied sources.
Researcher notes
Analysis is limited to the source bundle. The advisory identifies affected Microsoft products and a patch reference, but the bundle does not include exploit mechanics, proof-of-concept status, or detailed mitigation alternatives.
Mitigation direction
- Apply Microsoft security updates referenced in the MSRC advisory.
- Prioritize users who routinely handle external Access or Office files.
- Confirm affected Office and Access versions are still supported.
- Check Microsoft guidance for any product-specific workarounds or deployment notes.
Validation and detection
- Inventory endpoints for affected Microsoft Access and Office versions.
- Verify the relevant Microsoft security update is installed.
- Review patch management reports for failed Office update deployments.
- Confirm high-risk users no longer run vulnerable listed versions.
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-2025-21186 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 Access 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.