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What is CVE-2026-91403 (compromised eMudhra certificates) and the impact in Mendix on Kubernetes, Azure and Private Mendix Platform

Introduction

A widely used certificate authority called eMudhra generated the cryptographic keys for eight of its intermediate certificates incorrectly, which caused the certificates to be weak and compromised. This is tracked as CVE-2026-91403. Java, which Mendix apps run on, trusts these certificates by default. Someone able to intercept an app's outgoing connection could pose as the server it was calling.

Environment

Applications hosted in Mendix on Kubernetes

Applications hosted in Mendix on Azure

Private Mendix Platform

Details

Who is affected

Only the outgoing connections an app makes over HTTPS, for example REST or web service calls, or other integrations with external systems are affected. Traffic coming in to an app, such as users opening it in a browser, is not affected.

What Mendix has done

Mendix has an automated pipeline that automatically scans the Mendix on Kubernetes base images for CVEs and rebuilds the latest release. On 23 Oct 2026, this pipeline rebuilt Mendix on Kubernetes 2.28.1 and the hi-1-jre{{.JavaVersion}}-entrypointbase image.

The  ubi8-1-jre{{.JavaVersion}}-entrypoint and ubi9-1-jre{{.JavaVersion}}-entrypoint base Runtime base images were rebuilt later, and have the patch available starting from 16:30 UTC, 23 Oct 2026.

Actions Required To Apply Fix

Upgrade to Mendix Operator 2.28.1 (or a later version) to ensure that all internal containers are running a patched version. If an air-gapped copy of Mendix Operator (including version 2.28.1) or Private Mendix Platform (including version 2.8.1) is used, make sure it's updated (downloaded on 16:30 UTC, 23 October 2026 or later), and run a CVE scan on all images to confirm that the air-gapped images are not affected by this CVE.

After switching the base image, Mendix apps will need to be rebuilt and redeployed. The fix is added when the app is rebuilt, so apps that are already running only pick it up on a redeploy. A restart is not enough.

If the application makes outgoing calls to other systems, please redeploy it. Do this in the usual order for releasing changes (Test, Acceptance, then Production) and check that integrations still work before redeploying Production.

If the application does not make outgoing calls to third-party services, no action is needed. It will receive the update at its next regular deployment.

A redeploy causes a short downtime while the app restarts, so plan it in a convenient window.

What to expect after redeploying

If one of the systems an app calls uses a certificate issued by one of the affected eMudhra authorities, the connection will now fail.

In that case, ask the owner of that system to replace its certificate.

Internal information related

C0161BEMQ4B/p1792746527829549

Additional information

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