Security readout for executives and security teams
Plain-English summary
This high-severity Outlook flaw could let a locally authenticated, low-privileged user gain unauthorized access and alter sensitive information. The supplied evidence does not indicate availability impact or confirmed active exploitation. Organizations using the listed Microsoft 365 Apps for Enterprise version should prioritize Microsoft’s security update and verify deployment.
Executive priority
Treat this as a high-priority endpoint remediation, especially on systems handling sensitive information or accessible by multiple users. It is not supported as an emergency active-exploitation event by the supplied evidence, but its low complexity and potential confidentiality and integrity impact justify prompt patch verification.
Technical view
CVE-2024-21402 is an Outlook elevation-of-privilege vulnerability categorized as CWE-285. Its CVSS 3.1 score is 7.1: local access, low complexity, low privileges, and no user interaction, with high confidentiality and integrity impact but no availability impact. The bundle lists Microsoft 365 Apps for Enterprise 16.0.1; broader affected-version details are not provided.
Likely exposure
Exposure requires local access and existing low-level privileges, so compromised endpoints and shared systems are the main concern. The supplied affected-product data identifies Microsoft 365 Apps for Enterprise 16.0.1 only. Administrators should use Microsoft’s advisory to determine actual affected builds because the bundle does not establish broader version coverage.
Exploitation context
The CVSS vector indicates exploitation is local, low-complexity, requires low privileges, and needs no user interaction. The CVE is not marked as CISA KEV, and the supplied sources provide no evidence of active exploitation. Absence from KEV does not prove that exploitation is impossible or nonexistent.
Researcher notes
The supplied data provides scoring, CWE, one affected version, and Microsoft’s advisory, but not the vulnerable component, root cause, corrected builds, or exploitation evidence. Researchers should avoid inferring remote reachability: AV:L explicitly indicates local access. Use Microsoft’s advisory as the authoritative source for version applicability and remediation details.
Mitigation direction
- Review Microsoft’s CVE-2024-21402 advisory for affected builds and the applicable security update.
- Deploy Microsoft’s security update through the organization’s approved endpoint-management process.
- Prioritize shared, privileged, and already-compromised endpoints where local privilege escalation presents greater business risk.
- Restrict unnecessary local access and investigate endpoints showing signs of unauthorized account use.
Validation and detection
- Inventory installed Microsoft 365 Apps and Outlook builds across managed endpoints.
- Compare installed builds with the affected and corrected versions in Microsoft’s advisory.
- Confirm the applicable security update reports successful installation on in-scope endpoints.
- Re-scan or query managed endpoints to identify missed, failed, or rolled-back updates.
- Review endpoint telemetry for suspicious privilege changes or unauthorized access around Outlook activity.
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-285: 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2024-21402 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
- 7.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/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:L/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C1.85.2microsoftVulnerability scoring details
Base CVSS 3.1 score
7.1HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/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 Elevation of Privilege 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 Authorization
Improper Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.