CVE-2025-66478: How I Got Hacked and What You Must Do Now

That Heart-Stopping Moment: When Your Server Betrays You

You're casually checking htop on your home server—maybe you're tweaking resource allocation or just satisfying that sysadmin curiosity—when your eyes lock onto a process that shouldn't be there. A crypto miner. Running as root. Your stomach drops. That's exactly what happened to me last week, and it's happening to more self-hosters than you'd think.

The command looked something like this:

./hash -o auto.c3pool.org:13333 -u 45vWwParN9pJSmRVEd57jH5my5N7Py6Lsi3GqTg3wm8XReVLEietnSLWUSXayo5LdAW2objP4ubjiWTM7vk4JiYm4j3Aozd -p miner_1766113254 --randomx-1gb-pages --cpu-priority=0 --cpu-max-threads-hint=95

Monero mining. On my hardware. Using my electricity. And the worst part? It was hiding in plain sight inside a container I trusted. This wasn't some sophisticated nation-state attack—it was CVE-2025-66478 exploiting a vulnerability in a popular self-hosted application's container image. If you're running anything in containers (and who isn't these days?), you need to read this. I'll walk you through exactly what happened, how to check if you're affected, and most importantly, how to prevent it from happening to you.

Understanding CVE-2025-66478: More Than Just a Crypto Miner

At first glance, CVE-2025-66478 looks like your standard cryptojacking vulnerability—an attacker gets code execution and deploys a miner. But it's actually more insidious. The vulnerability exists in how certain container images handle environment variables and initialization scripts. Specifically, it's a path traversal combined with improper input validation that allows an attacker to write arbitrary files during container startup.

Here's what makes this particular CVE nasty: The malicious payload doesn't arrive through some obvious backdoor. It comes packaged inside what appears to be a legitimate container from a trusted source. The container itself might be perfectly functional—it runs your web UI, serves your files, does whatever it's supposed to do—but during initialization, it also drops and executes the mining binary.

And the miner isn't some amateur script kiddie tool. It's the XMRig miner, configured with professional-grade optimizations: --randomx-1gb-pages for better performance, --cpu-priority=0 to avoid being too obvious, and --cpu-max-threads-hint=95 to maximize resource usage while leaving just enough headroom to avoid complete system lockup. This is designed to fly under the radar.

The Container Compromise Chain: How It Actually Works

Let me break down exactly how this attack unfolds, because understanding the mechanics is half the battle for prevention. The vulnerability chain typically goes like this:

First, the attacker identifies a popular self-hosted application with a Docker image that has weak build practices. Maybe it's pulling dependencies from unverified sources, or it's using a multi-stage build where the final image inherits something it shouldn't. In the case of CVE-2025-66478, the issue was in how the entrypoint script processed certain environment variables.

During container startup, the malicious code gets executed with the same privileges as the container itself. And here's where most people get burned: They run containers as root because it's easier. No permission issues, no UID/GID mapping headaches. But when that container gets compromised, the attacker now has root access to the container environment.

From there, the miner gets downloaded (often from a legitimate-looking domain that's actually compromised) and executed. It runs persistently, restarting if killed, and communicates with the mining pool through what looks like normal outbound traffic. Unless you're specifically looking for it, you might never notice.

Detection: Finding the Needle in Your Server Stack

So how do you find these things before they've been running for months? The Reddit thread where I first shared my experience had dozens of people asking exactly this. Here's what I've learned from that discussion and my own investigation.

Start with the obvious: Check your running processes regularly. Not just with htop, but with ps auxf to see process trees. Look for anything with "hash," "xmrig," "miner," or suspicious domain names in the command line. But here's the thing—modern attackers are getting smarter. They rename binaries, use process hiding techniques, or run the miner only during off-hours.

You need to go deeper. Monitor your system's resource usage patterns. A crypto miner will show up as sustained high CPU usage, even when your applications should be idle. I use a combination of netdata for real-time monitoring and prometheus with grafana for historical trends. Set up alerts for abnormal CPU patterns—if a container is consistently using 80-95% CPU, that's a red flag.

Network monitoring is equally important. The miner in my case was connecting to auto.c3pool.org:13333. Tools like nethogs or iftop can show you which processes are making network connections. Even better, set up a firewall rule to log all outbound connections and review the logs periodically. Unusual destinations, especially to known mining pools, should jump out.

The Cleanup Process: Removing the Infection Completely

Finding the miner is only half the battle. You need to remove it completely, and that's trickier than it sounds. When I first discovered the infection, I made the rookie mistake of just killing the process. It came back within minutes.

Here's the proper cleanup procedure I developed through trial and error:

1. First, isolate the infected container. Don't just stop it—remove its network access immediately. Use docker network disconnect or, if you're using Docker Compose, bring down the entire stack.
2. Examine the container's filesystem. Use docker exec [container] find / -name "*hash*" -o -name "*xmrig*" -o -name "*miner*" to locate the binary. But remember—it might be renamed. Also check for suspicious files in /tmp, /dev/shm, and hidden directories.
3. Look for persistence mechanisms. Check crontab entries, systemd services, and startup scripts. The attacker might have installed a watchdog that restarts the miner if it dies.
4. Now, here's the critical part: Don't just remove the container. You need to understand how it got infected in the first place. Examine the Dockerfile if you have it, check the image source, and look for environment variables or mounted volumes that might have been the attack vector.
5. Finally, rotate all credentials that were stored on or accessible from that container. Assume they're compromised.

One pro tip from the Reddit discussion: Create a known-clean backup of your container configurations and data before you start poking around. That way, if you accidentally destroy something important during cleanup, you can restore from backup.

Prevention: Building a Fortress, Not Just a Firewall

Cleaning up after an attack is stressful. Preventing the next one is where you should focus your energy. Based on what I've learned—and what dozens of other self-hosters shared in the discussion—here's your new security baseline.

First, never run containers as root. Ever. I know it's convenient, but it's asking for trouble. Instead, create a non-root user inside your Dockerfile and use the USER directive. Even better, use Podman if you can—it runs containers rootless by default. The difference in security posture is dramatic.

Second, implement image signing and verification. Docker Content Trust isn't just for enterprises. Enable it with export DOCKER_CONTENT_TRUST=1 and only pull signed images. This won't catch everything, but it eliminates a whole class of attacks where someone uploads a malicious image to Docker Hub.

Third, use security scanning tools. I now run trivy or grype on every image before I deploy it. These tools check for known vulnerabilities, including CVE-2025-66478. Integrate them into your CI/CD pipeline if you have one, or at least run them manually before updating containers.

Fourth, implement network segmentation. Your containers shouldn't all be on the same network. Isolate services that don't need to talk to each other. Use a reverse proxy (I prefer Traefik) to manage ingress, and don't expose more ports than absolutely necessary.

Monitoring and Alerting: Your 24/7 Security Guard

Even with perfect prevention, you need monitoring. The reality is, new vulnerabilities emerge constantly. CVE-2025-66478 won't be the last of its kind.

Set up a monitoring stack that actually alerts you to problems. I use Prometheus with the node exporter and cAdvisor to collect metrics from both the host and containers. Grafana dashboards give me a visual overview, but the real magic is in Alertmanager. I've configured alerts for:

• Sustained high CPU usage (above 80% for more than 5 minutes)
• Containers spawning unexpected child processes
• Outbound connections to known malicious IPs (I update threat intelligence feeds regularly)
• Changes to container images or configurations

But here's what most guides don't tell you: You need to tune your alerts to avoid alert fatigue. Start with conservative thresholds and adjust based on your normal workload. A media server doing transcoding will have different CPU patterns than a database server.

Also, consider behavioral monitoring. Tools like Falco can detect suspicious container activities based on rules and machine learning. It's more complex to set up, but it catches things that signature-based tools miss.

Common Mistakes (And How to Avoid Them)

Reading through the 300+ comments on the original Reddit thread, I noticed patterns. People kept making the same mistakes. Let me save you the trouble.

Mistake #1: Using latest tags. I get it—it's convenient. But latest is a moving target. Today it might be clean, tomorrow it might contain CVE-2025-66478. Always use specific version tags, and update deliberately, not automatically.

Mistake #2: Blindly trusting Docker Hub. Anyone can upload an image to Docker Hub. Just because it has a familiar name doesn't mean it's legitimate. Stick to official images when possible, or better yet, build your own from trusted base images.

Mistake #3: Overprivileged containers. If your container needs to bind to port 80, it doesn't need --privileged flag or cap-add=ALL. Learn about Linux capabilities and grant only what's necessary. The principle of least privilege isn't just for users.

Mistake #4: No backup strategy. When I got hit, I was terrified I'd lose data if I nuked the container. Now I have automated backups using WD 4TB External Hard Drive for local storage and a cloud backup for critical data. Test your restore process regularly—backups you can't restore are worse than no backups at all.

Mistake #5: Thinking "it won't happen to me." This was my biggest mistake. I have a relatively obscure setup, I thought. Who would target me? The answer: automated scanners that don't care who you are. They probe every IP address looking for vulnerable software.

When to Bring in the Pros

Here's something I had to come to terms with: Sometimes, you need help. If you're running business-critical services on your home server, or if you've been compromised multiple times, it might be worth investing in professional security.

Platforms like Apify offer security monitoring and automation that can handle the constant vigilance required. They maintain threat intelligence feeds, update detection rules, and handle the infrastructure—freeing you to focus on your actual applications rather than security operations.

Alternatively, if you need custom security configurations or a one-time audit, consider hiring a specialist. Marketplaces like Fiverr have security professionals who can review your setup, identify vulnerabilities, and help you implement proper hardening. Sometimes an outside perspective catches things you've been overlooking for years.

The key is knowing your limits. I love self-hosting because of the control it gives me, but there's a difference between control and competence. If security isn't your expertise, getting help isn't failure—it's smart risk management.

Moving Forward: Security as a Mindset

Getting hit by CVE-2025-66478 was a wake-up call. It transformed how I think about my home lab. Security isn't a feature you add—it's a mindset that informs every decision, from which image you pull to how you monitor performance.

The most important lesson? Don't let perfect be the enemy of good. You don't need enterprise-grade security on day one. Start with the basics: non-root containers, image scanning, and basic monitoring. Then layer on more advanced protections as you learn.

Check your processes right now. Seriously, open a terminal and run ps aux | grep -i hash. Then set a calendar reminder to check again next week. Subscribe to security mailing lists for the software you use. Join communities like r/selfhosted where people share their experiences and warnings.

My server is cleaner and more secure now than it was before the attack. The miner is gone, my monitoring is better, and I sleep easier knowing I'm not accidentally donating my electricity to some anonymous cryptojacker. Take these lessons, apply them to your setup, and maybe—just maybe—you'll avoid that heart-stopping moment I experienced.

Because in the world of self-hosting, the only thing worse than finding a crypto miner on your server is not finding it.