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High

Azure Entra ID Sensitive Information Exposure Leading to Spoofing

IdentifiersCVE-2026-40379CWE-200· Exposure of Sensitive Information…

CVE-2026-40379 is an information disclosure vulnerability in Azure Entra ID. According to the provided content, the issue is an exposure of sensitive information to an unauthorized actor that can be leveraged to perform spoofing over a network. The available material does not identify the specific vulnerable component, function, protocol flow, or token/credential artifact exposed. Microsoft characterized the issue as requiring no customer action, which suggests the vulnerable condition was remediated service-side in the Azure Entra ID platform.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an unauthorized remote attacker to use exposed sensitive information to spoof identities or authentication-related artifacts over the network. The practical impact is impersonation or fraudulent representation within workflows that rely on Azure Entra ID trust or identity assertions. The provided content does not specify whether this results in direct account takeover, token forgery, session hijacking, or downstream access to particular resources.

Mitigation

If you can’t patch tonight, do this now.

No specific mitigation is provided in the supplied content beyond Microsoft's statement that no customer action is required. As general risk reduction for identity spoofing scenarios, organizations can strengthen monitoring of Entra ID sign-in activity, enforce MFA, remove legacy authentication paths, and apply strong access controls, but these are general defensive measures rather than vulnerability-specific mitigations documented for CVE-2026-40379.

Remediation

Patch, then assume compromise.

Microsoft has already patched the vulnerability in Azure Entra ID, and the provided content states that it requires no customer action. Remediation therefore appears to be service-side within Microsoft's cloud environment. Organizations should verify they are operating on supported integrations and continue normal monitoring for suspicious identity activity, but no specific customer-applied patch or configuration change is identified in the provided material.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft CorporationAzure Enterprise Security Token Serviceapplication
Microsoft CorporationEntra Idapplication
Microsoft CorporationMicrosoft Entra Idapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

3 SOURCESView more in app
What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity2

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-40379
NVD
nvd.nist.gov/vuln/detail/CVE-2026-40379
MITRE CWE · CWE-200
Exposure of Sensitive Information to an…
Vendor Advisory
msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40379