Security readout for executives and security teams
Plain-English summary
This is a high-severity Microsoft OneNote remote code execution issue. The available scoring says an attacker must convince a user to interact with a malicious local item, but no privileges are required. Successful exploitation could compromise confidentiality, integrity, and availability on the affected system.
Executive priority
Treat this as a priority patching item for user workstations, not an internet-edge emergency. Business risk comes from user-assisted compromise through Office content, with potentially full impact on affected endpoints if exploitation succeeds.
Technical view
CVE-2025-21402 affects Microsoft OneNote and Office LTSC for Mac 2021/2024 versions listed by the CVE bundle. CVSS 3.1 is 7.8 with AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. The bundle maps it to CWE-641 and identifies Microsoft’s advisory as the patch source.
Likely exposure
Exposure is most likely where affected Microsoft OneNote or Office LTSC for Mac installations are present, especially endpoints handling untrusted notes or attachments. The source bundle does not provide deployment prevalence or exact fixed build details.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation evidence. User interaction is required by the CVSS vector, so phishing, shared files, or downloaded OneNote content are plausible risk contexts, but no exploit method is provided in the sources.
Researcher notes
Do not assume exploitation in the wild from the provided evidence. The key constraints are local attack vector and required user interaction, with no privileges required. Microsoft’s advisory is the authoritative place for fixed versions and deployment guidance.
Mitigation direction
- Review Microsoft MSRC CVE-2025-21402 and apply the applicable Office or OneNote security update.
- Prioritize endpoints where OneNote opens files from email, chat, browser downloads, or shared drives.
- Use endpoint controls to block or quarantine suspicious OneNote files until patched.
- Confirm Microsoft 365 or Office update channels are reaching affected Mac and OneNote installations.
Validation and detection
- Inventory Microsoft OneNote and Office LTSC for Mac 2021/2024 installations.
- Compare installed versions against Microsoft’s CVE-2025-21402 guidance.
- Check endpoint management reports for successful Office or OneNote update installation.
- Review security telemetry for unusual OneNote-launched child processes or suspicious file-open events.
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-641: 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-2025-21402 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/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/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/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 Office OneNote 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.
Improper Restriction of Names for Files and Other Resources
Improper Restriction of Names for Files and Other Resources represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.