CVE-2026-109485

An authorized Agents SDK caller could make unintended network requests

Microsoft · Microsoft 365 Agents SDK for .NET

First documented disclosure · Review checkpoint

Summary

The SDK allowed a caller to influence a request sent by the service. Information reachable from the service could be disclosed over the network.

Severity and exploitation evidence

Medium · 6.3/10 · CVSS 3.1. Severity source.

Exploitation not established: Microsoft marked exploitation as No at publication.

Exploitation evidence source

Technical severity is not a measure of observed attacks or of risk to your deployment. Attempts, demonstrations, and successful compromise retain the qualifications in the source.

How the weakness works

The SDK allowed a caller to influence a request sent by the service.

Conditions required

A signed-in caller could reach a deployment using the affected SDK.

Potential impact

Information reachable from the service could be disclosed over the network.

Affected versions and configurations

MSRC identifies the .NET SDK. The CNA's numeric lower bound exceeds its fixed version.

Fix and mitigation status

1.8.77, per the MSRC remediation and linked Agents-for-net release.

Practical next steps

Update the .NET Agents SDK to 1.8.77 or later.

Operating lesson

Track the deployed SDK, extension or managed service when applying Microsoft’s remediation.

Evidence and limits

The CVE record was published on 2026-11-10.

Sources