{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/azure-entra-id/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Enterprise Security Token Service","Azure Entra ID"],"_cs_severities":["medium"],"_cs_tags":["entra_id","spoofing","cloud"],"_cs_type":"advisory","_cs_vendors":["Microsoft"],"content_html":"\u003cp\u003eCVE-2026-40379, disclosed on May 7, 2026, describes a spoofing vulnerability within the Microsoft Enterprise Security Token Service (ESTS) related to Azure Entra ID. This vulnerability can lead to the exposure of sensitive information to unauthorized actors, potentially allowing them to perform spoofing attacks over a network. The vulnerability lies within the ESTS component, and successful exploitation could allow an attacker to impersonate legitimate users or services within the Azure Entra ID environment. Defenders need to ensure proper configuration and monitoring of their Azure Entra ID environments to mitigate the risk posed by this vulnerability.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker identifies a vulnerable ESTS configuration within an Azure Entra ID environment.\u003c/li\u003e\n\u003cli\u003eThe attacker exploits CVE-2026-40379 to gain unauthorized access to sensitive information related to ESTS.\u003c/li\u003e\n\u003cli\u003eThe exposed information is used to craft malicious security tokens.\u003c/li\u003e\n\u003cli\u003eThe attacker uses the spoofed tokens to authenticate to other services within the Azure Entra ID environment.\u003c/li\u003e\n\u003cli\u003eThe attacker gains access to resources and data that they are not authorized to access.\u003c/li\u003e\n\u003cli\u003eThe attacker performs actions impersonating a legitimate user or service.\u003c/li\u003e\n\u003cli\u003eThe attacker may escalate privileges within the Azure Entra ID environment.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-40379 can lead to unauthorized access to sensitive resources and data within an organization\u0026rsquo;s Azure Entra ID environment. An attacker could potentially impersonate legitimate users or services, leading to data breaches, financial loss, or disruption of business operations. The scope of the impact depends on the permissions and access levels of the compromised user or service.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMonitor Azure Entra ID logs for suspicious authentication attempts and token issuance patterns that may indicate exploitation of CVE-2026-40379.\u003c/li\u003e\n\u003cli\u003eDeploy the provided Sigma rule to detect suspicious token activity based on CVE-2026-40379.\u003c/li\u003e\n\u003cli\u003eReview and harden ESTS configurations within Azure Entra ID to minimize the attack surface and potential for information exposure.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-07T14:00:00Z","date_published":"2026-05-07T14:00:00Z","id":"/briefs/2024-01-23-ests-spoofing/","summary":"CVE-2026-40379 is a spoofing vulnerability in Microsoft Enterprise Security Token Service (ESTS) where exposure of sensitive information in Azure Entra ID allows an unauthorized attacker to perform spoofing over a network.","title":"CVE-2026-40379 Microsoft Enterprise Security Token Service (ESTS) Spoofing Vulnerability","url":"https://feed.craftedsignal.io/briefs/2024-01-23-ests-spoofing/"}],"language":"en","title":"CraftedSignal Threat Feed — Azure Entra ID","version":"https://jsonfeed.org/version/1.1"}