If you're one of the thousands of creators building your livelihood on Substack—earning five, six, or even seven figures from your newsletter—this investigation will make you uncomfortable. And it should. Let’s disrupt Substack.

You've spent years building your subscriber list… You've cultivated trust with thousands of readers who pay you monthly for your insights. You've built a brand that people recognize and respect. But what if I told you that a single security vulnerability could allow someone to hijack your domain, impersonate your brand, and potentially steal your entire audience?

That's exactly what's happening to many high-traffic websites, and also on Substack right now.

In March 2025, a security researcher uncovered a critical flaw in how Substack handles custom domains—those professional-looking URLs that separate serious creators from hobbyists. The vulnerability is as elegant as it is terrifying: for just $50, an attacker can hijack abandoned domains and serve malicious content under established creator brands.

Here's how it works, and why it should keep every serious Substack creator awake at night.

When you set up a custom domain on Substack (like newsletter.yourname.com instead of yourname.substack.com), you create what's called a CNAME record in your domain's DNS settings. This record tells the internet: "When someone visits my custom domain, redirect them to Substack's servers."

The problem? Substack doesn't verify that you actually own the domain you're claiming (yikes).

Most legitimate services require you to prove domain ownership by adding a special TXT record to your DNS—a kind of digital signature that says "Yes, I control this domain." Substack skips this step entirely. They only check if the CNAME record exists, not if you're authorized to use it.

This creates a dangerous window of opportunity.

When creators abandon their Substack blogs but forget to clean up their DNS records (and this happens more often than you'd think), those domains become sitting ducks. An attacker can simply add the abandoned domain to their own Substack account, pay the $50 custom domain fee, and suddenly they're hosting content under your old domain—complete with a valid SSL certificate that makes everything look legitimate.

A security researcher analyzed 16,925 domains pointing to Substack's infrastructure. The results were alarming:

But here's what makes this particularly insidious: the attack doesn't just work on truly abandoned domains. It works on ANY domain where the DNS records are misconfigured or where creators have made common setup mistakes.

If you're earning money on Substack (first of all, congrats), this vulnerability threatens you in ways that go far beyond embarrassment:

Brand Impersonation Attacks Imagine a scammer taking over an old domain associated with your name and using it to:

Revenue Theft A sophisticated attacker could:

Legal Liability If someone uses a hijacked domain associated with your brand to:

You could face legal consequences, even though you weren't directly responsible for the attack!

Substack's reliance on Cloudflare for SaaS to handle custom domains creates a sophisticated but flawed system. When you add a custom domain, Substack configures Cloudflare to route traffic from your domain to their servers. This system works beautifully—until it doesn't.

The platform essentially treats domain verification as a payment problem rather than a security problem. Pay $50, prove you can set up a CNAME record, and you're in. No additional verification required.

This might seem like a reasonable approach for a platform focused on ease of use, but it ignores a fundamental principle of internet security: never trust, always verify.

Let me paint you a scary picture of how this could unfold:

Scenario 1: The Abandoned Test Domain You're a successful creator earning $10,000/month from your newsletter! Woohoo. Two years ago, when you were just starting out, you experimented with a custom domain for a side project that never took off (haven’t we all). You forgot about it, but the DNS records are still pointing to Substack.

An attacker discovers this domain, claims it, and sets up a fake newsletter that looks exactly like your current one. They use this to:

By the time you discover the attack, hundreds of your subscribers have been scammed, and your reputation is in ruins.

Scenario 2: The Wildcard Catastrophe You set up a wildcard CNAME record (*.yourdomain.com) to handle multiple newsletter projects. You abandon one project but leave the DNS configuration in place.

An attacker now has access to unlimited subdomains under your brand:

Each subdomain comes with a valid SSL certificate, making the scams appear completely legitimate to your audience.

Scenario 3: The Competitor Attack A rival creator in your niche identifies your old experimental domains and uses them to:

This vulnerability highlights a broader issue that's becoming increasingly critical as the creator economy matures. Platforms like Substack aren't just hosting hobby blogs anymore—they're supporting professional creators who've built entire businesses on these platforms.

When a creator is earning six figures annually and supporting their family through their Substack income, a security vulnerability isn't just a technical problem—it's a threat to their livelihood.

Yet many platforms (Wordpress, Shopify, Wix), including Substack, still operate with the security mindset of a simple blogging service rather than the business-critical infrastructure they've become.

The fix for this vulnerability is straightforward and industry-standard:

Implement proper domain verification using TXT records to prove ownership before allowing custom domain setup. Cloudflare for SaaS, which Substack already uses, supports this verification method—Substack simply isn't using it.

Add proactive monitoring to detect and disable orphaned domain configurations automatically.

Provide security dashboards so creators can monitor the status of their domains and receive alerts about potential issues.

Establish clear incident response procedures for when domain takeovers do occur.

The platform has a formal vulnerability disclosure program and seems committed to security in principle. But good intentions don't protect creators who are losing money to security incidents right now.

While we wait for Substack to implement proper fixes, here's what you can do to protect yourself:

Audit Your Domain Portfolio

Implement Domain Monitoring

Practice Defense in Depth

Plan for Incident Response

This Substack vulnerability is a canary in the coal mine for the broader creator economy. As more creators build substantial businesses on third-party platforms, we're discovering that these platforms' security practices haven't kept pace with the economic realities of their user base.

Platform Dependency Risk When your income depends on a platform's security, you're only as secure as their weakest link. Creators need to demand better security practices from the platforms they depend on.

The Need for Creator Security Education Most creators aren't cybersecurity experts, but they're running businesses that require security expertise. There's an urgent need for better security education targeted specifically at the creator community.

Insurance and Risk Management As creator businesses become more valuable, traditional business protections like cyber liability insurance become essential. Yet most creators haven't considered these protections.

Substack isn't the only newsletter platform with security challenges. As this industry matures, platforms need to recognize that they're not just providing publishing tools—they're providing business infrastructure.

That means implementing enterprise-grade security practices:

Platforms that fail to adapt to these higher security standards will find themselves losing creators to more security-conscious competitors.

Substack's current approach treats the $50 custom domain fee as a security control—the theory being that requiring payment will deter casual attackers. This fundamentally misunderstands how modern cybercrime works.

For attackers targeting high-value creators with substantial subscriber lists, $50 is trivial. The potential return on investment from a successful attack could be thousands or tens of thousands of dollars.

Real security controls don't rely on economic deterrents—they rely on technical barriers that make attacks impossible, not just expensive.

If you're a creator earning substantial income on Substack (or any newsletter platform), you have more power than you might realize. Platforms respond to pressure from their most valuable users.

Here's what you can do:

Demand better security from Substack and other platforms you use. Make it clear that security isn't a nice-to-have feature—it's essential business infrastructure.

Share security information with other creators in your network. Many creators aren't aware of these risks and need to be educated.

Diversify your platform dependencies where possible. Don't put all your creator economy eggs in one platform's basket.

Invest in your own security education. Understanding basic cybersecurity concepts isn't optional for serious creators anymore.

The security researcher who discovered this vulnerability followed responsible disclosure practices, giving Substack time to address the issue before making it public. This is the right approach—but it also means the vulnerability existed (and may still exist) for months before creators became aware of it.

This highlights the importance of platforms being proactive about security rather than reactive. Waiting for researchers to find vulnerabilities isn't a security strategy—it's security by accident.

As the creator economy continues to grow, we'll see increasing focus on platform security. Creators are beginning to understand that their choice of platform isn't just about features and audience—it's about the security of their business.

Platforms that invest in robust security practices will attract the most valuable creators. Those that don't will find themselves relegated to hobbyist users who can afford to take security risks.

What to watch for:

The domain takeover vulnerability in Substack's custom domain system represents more than just a technical problem—it's a wake-up call for the entire creator economy.

If you're building a business on Substack or any other creator platform, you can no longer afford to ignore security considerations. Your income, your reputation, and your audience's trust all depend on understanding and mitigating these risks.

The good news is that awareness is the first step toward protection. By understanding how these attacks work and taking proactive steps to protect yourself, you can continue building your creator business with confidence.

But don't expect the platforms to protect you automatically. In the creator economy, just like in any other business, security is ultimately your responsibility.

How to take action today:

Your creator empire is worth protecting. Don't let a $50 vulnerability destroy what you've spent years building.

Sources and Further Reading:

This article is based on publicly disclosed security research and is intended to educate creators about cybersecurity risks. If you discover security vulnerabilities in any platform, please follow responsible disclosure practices.

About the Author - An electronic warfare specialist, cybersecurity researcher, and “ethical” hacker striving to expose security vulnerabilities to supercharge the evolution of security.

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