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. Risk is Critical (CVSS 10.0) across any Microsoft kit you run. Follow the remediation in the vendor advisory within Immediate — CISA KEV entries carry a federal remediation deadline.
Why it matters:
- Exposure depends on deployment topology and which access paths reach the affected component.
- Treat internet-facing and management-plane instances as higher risk than internal-only ones.
- Keep monitoring for abnormal authentication and configuration events until upgrades complete.
Now / Next / Later:
- Now: confirm whether you run the affected versions, and check exposure of any that are internet-facing.
- Next: apply the remediation the advisory specifies, through an approved change window.
- Later: add a control check so builds cannot drift back onto a vulnerable train.