Security readout for executives and security teams
Plain-English summary
A critical Microsoft Entra vulnerability can expose sensitive information and let an unauthenticated network attacker impersonate a trusted party. Successful exploitation requires user interaction. The available sources do not identify affected versions or configurations, so organizations should treat Entra deployments as potentially exposed until Microsoft guidance confirms scope and remediation status.
Executive priority
Treat this as an immediate identity-security priority because compromise could affect sensitive information and trusted identity interactions. Assign ownership now, establish Microsoft-defined exposure, confirm remediation across all tenants, and monitor for suspicious activity. Escalate unresolved scope rather than assuming cloud services are automatically protected.
Technical view
CVE-2026-40379 is classified as CWE-200. Its CVSS 3.1 score is 9.3: network-accessible, low complexity, no privileges required, user interaction required, changed scope, high confidentiality and integrity impact, and no availability impact. The source bundle provides no technical root cause or affected-version details.
Likely exposure
Potential exposure applies to organizations using Microsoft Entra, but the supplied affected-version field is unspecified. Exact tenant configurations, services, and remediation coverage cannot be determined from the source bundle alone.
Exploitation context
The source bundle does not support active exploitation, and the CVE is not listed as KEV. The CVSS exploit-maturity value is unproven. Nevertheless, remote reachability, low complexity, and no authentication requirement make timely remediation important.
Researcher notes
Public details are sparse. The record identifies sensitive-information exposure enabling network spoofing but does not explain the vulnerable component, trust boundary, affected versions, or attack workflow. User interaction is required. Researchers should avoid inferring a specific protocol or identity flow and follow the Microsoft advisory for technical scope.
Mitigation direction
- Review the Microsoft advisory and apply its specified update or remediation promptly.
- Confirm remediation coverage across every Microsoft Entra tenant and environment.
- Restrict unnecessary identity administration access while remediation status is being established.
- Monitor Entra security and audit telemetry for suspicious unauthorized activity.
- Warn users to treat unexpected identity prompts or messages cautiously until remediation is confirmed.
Validation and detection
- Compare each Entra environment against the affected scope in Microsoft's advisory.
- Verify Microsoft's prescribed remediation is applied or confirmed effective for every tenant.
- Review relevant identity and audit logs for unexpected access or impersonation indicators.
- Use only Microsoft-approved, non-destructive validation methods to confirm remediation.
- Document environments where affected-version or configuration status remains unresolved.
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-200: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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-2026-40379 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
- Critical
- CVSS
- 9.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C2.85.8microsoftVulnerability scoring details
Base CVSS 3.1 score
9.3CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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
- Azure Entra ID Spoofing 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.