# Security maintenance completed: CVE-2026-99999

> Full URL: https://kumo2.com/ja/blog/security-maintenance-cve-2026-99999
> Summary: Scheduled security maintenance is complete. Kernel updates for CVE-2026-99999 are active, affected cloud servers have restarted, and platform services have passed recovery checks.
> Published: 2026-10-19
> Reviewed: 2026-10-19
> Reading time: 2 min
> Tags: 最新ニュース, 運用
> Authors: Ty (テクニカルエキスパート) - https://kumo2.com/ja/team/ty
> Author intro: Ty (テクニカルエキスパート): Ty は Kumo2 のユーザーとチームが技術要件を信頼できる実用的なインフラに落とし込めるよう支援します。
> Reviewed by: Ty (テクニカルエキスパート) - https://kumo2.com/ja/team/ty
> Review basis: Ty (テクニカルエキスパート): Ty は公開前に Kumo2 の技術コンテンツを確認し、運用上の正確性、再現可能な手順、リスク説明の明確さを見ます。
> Markdown locale: en

We have completed the scheduled security maintenance for **CVE-2026-99999**. The kernel security update is now active, affected cloud servers have restarted, and platform services have passed recovery checks.

Thank you for your patience during the maintenance window.

## Why this update was needed

CVE-2026-99999 is a Linux kernel vulnerability that can allow a malicious virtual machine to compromise its host through the virtual networking stack. We applied the upstream security update and restarted the affected infrastructure to activate the fixed kernel.

## Maintenance timeline

All times below are in UTC on **October 19, 2026**.

- **16:00:** The scheduled maintenance window began.
- **16:02:** The infrastructure restart was initiated after pre-maintenance checks.
- **16:08:** Cloud servers that had been running before maintenance had restarted.
- **16:09:** Website, API, background worker, and database recovery checks passed. Object storage had also passed its recovery checks.
- **16:11:** Final infrastructure and service verification was completed.

## Service impact

Affected cloud servers restarted during the maintenance window. The control panel, API, and LAX object storage experienced temporary interruptions while the infrastructure and services restarted.

Cloud servers that were powered off before maintenance were kept powered off.

## What we verified

- The updated kernel was running after the restart, making the security fix active.
- Virtualization services, storage, and infrastructure health checks passed.
- Cloud server power states matched their pre-maintenance states.
- The website, API, background worker, and database passed health checks.
- Object storage services were healthy, and the public S3 endpoint responded as expected.

These checks cover infrastructure and platform services. They do not verify every application running inside customer cloud servers.

## What customers should do

No additional customer-initiated reboot is required for this host-level security update. Please check that your applications and scheduled jobs have resumed as expected.

If your server remains unreachable or a service has not recovered, please [contact support](/contact) with your server ID or affected service details. You can also check the [status page](https://status.kumo2.com) for service updates.

## References

This notice is based on our maintenance records and the checks completed after the restart. For technical details about the vulnerability and upstream fixes, see:

- [Proxmox security advisory: CVE-2026-99999](https://forum.proxmox.com/threads/proxmox-virtual-environment-security-advisories.149331/post-873167)
- [Debian Security Tracker: CVE-2026-99999](https://security-tracker.debian.org/tracker/CVE-2026-99999)