Microsoft Entra ID Deserialization of Untrusted Data Vulnerability
TL;DR 📌
- Microsoft Entra ID formerly known as Azure Active Directory contains a deserialization of untrusted data vulnerability which could allow an unauthorized attacker to execute code over a network.
- Highest CVSS: 10.0 (Critical).
- Listed in CISA KEV (2026-08-21) — this is being exploited in the wild.
- Check the advisory for fixed releases — remediation detail is in the vendor link below.
- CVEs: CVE-2026-69836.
What it is
CVE-2026-69836 is a deserialization of untrusted data vulnerability in Microsoft Entra ID (formerly Azure Active Directory). Deserialization flaws of this type typically arise when an application reconstructs objects from attacker-supplied data without adequately validating it first, allowing crafted input to trigger unintended code execution.
The CVSS vector confirms this is exploitable over the network, with no privileges required and no user interaction needed. The attack complexity is rated low, and the scope is changed, meaning a successful exploit can affect resources beyond the vulnerable component itself. Confidentiality, integrity and availability are all rated high impact.
Given that Entra ID is Microsoft’s cloud identity and access management service, this sits in the management plane for authentication and directory services rather than in a specific network appliance. An unauthenticated attacker able to reach the vulnerable interface over the network can execute code, according to Microsoft’s own summary.
This CVE is listed in CISA’s Known Exploited Vulnerabilities catalogue, added on 21 August 2026. No fixed release information is included in the advisory at this time; consult Microsoft’s advisory directly for remediation guidance as it becomes available.
What to do
- Check Microsoft’s advisory for CVE-2026-69836 directly, as this brief does not have fixed-release details to point you to.
- Given the KEV listing, treat this as an active priority: confirm with your Microsoft tenant administrators whether any mitigation or patch has been issued, and apply it as soon as it is available.
- Review Entra ID sign-in and audit logs for anomalous authentication or directory activity, since this is a cloud identity service and conventional network-perimeter controls will not protect against it.
- Ensure your incident response and identity teams are aware of this CVE specifically, given the maximum CVSS score and the absence of required privileges or user interaction.
- Subscribe to Microsoft’s security update notifications for Entra ID so that a fix, if and when published, is applied without delay.
For leadership 🧭
Executive summary. A critical, actively exploited flaw in Microsoft Entra ID (formerly Azure Active Directory) allows unauthenticated remote code execution against the tenant’s identity and access management plane. This needs immediate attention from identity and incident response teams today, not at the next scheduled patch cycle.
Why it matters:
- Entra ID is the cloud identity and directory service underpinning authentication for Microsoft 365 and connected applications, so compromise here reaches far beyond a single server or appliance.
- The CVSS 10.0 score reflects no privileges required, no user interaction, low attack complexity, and a changed scope, meaning impact extends to resources beyond the vulnerable component itself.
- Confirmed inclusion in CISA’s Known Exploited Vulnerabilities catalogue means this is not theoretical; it is being used in the wild against organisations right now.
- Because this sits in the identity management plane rather than a network appliance, conventional perimeter defences such as firewalls will not stop an attacker exploiting it.
Now / Next / Later:
- Now: Contact your Microsoft tenant administrators immediately to confirm whether Microsoft has issued a mitigation or patch for CVE-2026-69836 and apply it the moment it is available.
- Next: Review Entra ID sign-in and audit logs for anomalous authentication or directory activity that could indicate exploitation, and brief incident response and identity teams specifically on this CVE.
- Later: Subscribe to Microsoft’s security update notifications for Entra ID and build a process for tracking identity-plane advisories separately from perimeter and endpoint patching, since this class of flaw bypasses network controls entirely.