Microsoft has patched a major attack vector for Azure Entra ID – CVE-2025-55241 – in record time. This vulnerability might have allowed bad actors to impersonate any user, including Global Administrators, in all tenants. Discovery In May 2023, security researcher Dirk-jan Mollema identified a critical CVE. With a CVSS score of up to 10.0, the vulnerability was disclosed on July 14 of this year. On July 17, 2025, Microsoft published an emergency patch for the vulnerability. It required customers to perform unnecessary steps to address their issue.
The king pin validation failure was the root cause of the Azure Entra ID vulnerability. This system is particularly important when it comes to authenticating services such as SharePoint Online and Exchange Online. The bug was related to the deprecated Azure AD Graph API. It did not sufficiently validate the originating tenant, opening it up to mass exploitation.
Details of the Vulnerability
CVE-2025-55241 is a critical security vulnerability that allows attackers to impersonate any user in the Azure Entra environment. This includes compromising Global Administrator accounts, which give nearly unlimited access to all resources hosted on Azure. Dirk-jan Mollema explained how grave the defect was, saying,
“It would also provide full access to any resource hosted in Azure, since these resources are controlled from the tenant level and Global Admins can grant themselves rights on Azure subscriptions.”
The internet-facing presence of this vulnerability makes it especially dangerous. It would allow malicious attacks against tenants across the globe, risking the integrity of millions of non-profit and for-profit enterprises that use Azure Entra ID as their backbone.
As security researchers Yoann Dequeker and Arnaud Petitcol found, attackers have a few different techniques to use against you. They can take advantage of this vulnerability without drawing attention or having to leverage malware. They stated,
“Techniques such as AccessKey injection, trust policy backdooring, and the use of NotAction policies allow attackers to persist without deploying malware or triggering alarms.”
Due to the interconnected nature of cloud services today, the prospect of cross-tenant attacks cause alarm in the minds of every IT security pro.
Impact on Azure Services and API
The vulnerability didn’t stop there – it affected API connections in Azure, as well. Haakon Holm Gulbrandsrud noted that using CVE-2025-55241 would give attackers full access to other sessions around the world. He stated,
“API Connections allow anyone to fully compromise any other connection worldwide, giving full access to the connected backend.”
This security risk doesn’t stop short at impersonating users. It opens the door for gaining access to sensitive resources such as Key Vaults and Azure SQL Databases. These services are essential for commercial companies who build their own services on top of Azure’s infrastructure.
The now deprecated Azure AD Graph API only adds to the confusion as it provided no validation measures. Roei Sherman emphasized this point, noting that
“The vulnerability arose because the legacy API failed to validate the tenant source of the token.”
Microsoft recommends transitioning to Microsoft Graph for enhanced security and functionality.
Mitigation Efforts and Recommendations
In recognition of this exposure, Microsoft has moved rapidly to protect users from potential threats related to CVE-2025-55241. It promised customers that they wouldn’t have to do anything to fix the breach. It underscored its commitment to ensure security within its own cloud infrastructure.
National cloud deployments at least have a distinct set of alternative vulnerabilities. All organizations must ensure their security measure and now use Microsoft Graph over the deprecated API. This transition improves security and efficiency while reflecting new best practices in identity and access management.