Cybersecurity flaws come in many forms. While most affect operating systems, libraries, or web apps, some go after a less obvious but equally critical target: DNS servers. Over the years, several CVEs affecting DNS servers have been discovered, and some of them rank among the most serious security risks out there.
DNS is what makes the internet usable by translating domain names into IP addresses. If that process is compromised, the impact can ripple across everything. According to CVE.org, over 286,000 vulnerabilities have been reported so far, and DNS-related issues are increasingly on that list. With Cloudflare controlling about 14.6% of the DNS market, it’s clear these servers are high-value targets.
So, let’s take a closer look at some of the most significant CVEs affecting DNS servers and what you can do to stay ahead of them.
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CVEs Explained
CVEs (short for Common Vulnerabilities and Exposures) are identifiers for publicly known security flaws. RedHat defines CVE as “a list of publicly disclosed computer security flaws.”
Among them, CVEs affecting DNS servers have gained more attention in recent years due to their potential to disrupt core internet services.
CVEs help defenders track, patch, and protect against known weaknesses. DNS servers, which are the backbone of Internet name resolution, are prime targets because compromising one can cascade into broader attacks.
Attacks like spoofing, cache poisoning, and remote code execution can put entire networks at risk. Many stem from CVEs affecting DNS servers, issues that often fly under the radar compared to flashier vulnerabilities.
Why DNS Vulnerabilities Matter
DNS is the internet’s phonebook, translating domain names into IP addresses so you can reach websites and services. When this process is compromised, the impact can be severe. Attackers can redirect traffic to malicious sites, intercept sensitive data, or even cause large-scale outages. Several of these scenarios originate from CVEs affecting DNS servers.
Attackers also abuse DNS flaws to spin up phishing subdomains that look legitimate, tricking users into handing over sensitive data.
DNS vulnerabilities can allow attackers to execute remote code, effectively taking control of entire systems. Beyond security, the business impact can include downtime, loss of trust, and significant financial damage.
Since DNS sits at the core of how the Internet works, even one weakness can have a ripple effect across systems and services. That’s why staying on top of patches and keeping an eye on CVEs targeting DNS systems is so important. Ignoring them can lead to serious financial and reputational damage.
Common DNS Software Targets
Several DNS implementations are widely used across the internet, and history shows that none are immune to vulnerabilities. When combined with security misconfigurations, these weaknesses can make DNS servers even more exposed.
Some of the most commonly targeted DNS servers include:
- BIND (Berkeley Internet Name Domain): The most widely used DNS software on Unix-based systems.
- Microsoft DNS Server: Integrated with Windows Server, often used in enterprise environments.
- Unbound: A validating, recursive, caching DNS resolver.
- PowerDNS: Popular for its flexibility and high-performance capabilities.
- Knot DNS: Known for speed and often used by TLD operators.
Notable CVEs Affecting DNS Servers
Over the past few years, several critical CVEs affecting DNS servers have come to light, revealing just how vulnerable these core systems can be.
One of the most notorious examples is CVE‑2020‑1350, better known as SIGRed. This flaw affected Microsoft DNS servers and was classified as wormable, meaning it could spread without user interaction. With a maximum CVSS score of 10, it allowed remote code execution with system-level privileges, a nightmare scenario for any administrator.
Another serious issue was CVE‑2021‑25215, which impacted BIND. This vulnerability involved a buffer overflow that could crash the server or, in some cases, allow attackers to execute arbitrary code. BIND has seen other problems too, including CVE‑2022‑2795 and CVE‑2022‑0396, both of which could lead to denial-of-service attacks by sending specially crafted queries to the server.
More recently, CVE‑2023‑50868 brought attention to DNSSEC implementations. This flaw allowed attackers to exploit the NSEC3 mechanism, forcing servers to perform expensive cryptographic operations repeatedly. The result? CPU exhaustion and potential outages.
These examples show how wide the attack surface really is, from buffer overflows to resource exhaustion. Keeping track of them and applying patches promptly is essential to avoid being the next victim.
How These Vulnerabilities Are Exploited
Attackers usually target DNS flaws to gain control or cause disruption. Common methods include:
- Remote Code Execution: As seen in CVE‑2020‑1350 (SIGRed), attackers could execute commands on the DNS server without authentication.
- Denial-of-Service (DoS): Vulnerabilities like CVE‑2022‑2795 allow attackers to send malformed packets that crash the service.
- Resource Exhaustion: DNSSEC-related issues can overload servers by exploiting cryptographic operations, leading to service degradation.
Why These CVEs Linger in Networks
Despite patches being available, many organizations delay updates because DNS servers are core infrastructure, and downtime during patching can be risky. In other cases, administrators simply overlook older CVEs or assume existing firewall rules offer enough protection. This leaves systems vulnerable for months or even years.
How to Reduce Your Risk
Protecting your DNS servers comes down to a mix of regular maintenance and smart configuration. Start with the basics: keep your DNS software updated. Most major exploits target known flaws, so timely patching is your first line of defense.
By using our web misconfiguration scanner, you can analyze the security of your DNS protocols to detect all kinds of flaws in your DNS security.
It’s also a good idea to reduce exposure. Don’t leave DNS servers wide open on the internet; restrict access as much as possible and place them behind firewalls. If you’re using DNSSEC, configure it carefully. While it adds an important layer of security, improper setup can make your server more vulnerable to resource exhaustion attacks.
Finally, keep an eye on your traffic. Sudden spikes in queries or unusually large responses can be a red flag. Adding rate limiting to your DNS service can also help absorb attacks without taking your systems offline.
Bottom Line
DNS keeps the internet running, but that also makes it a prime target. A single unpatched vulnerability can lead to massive outages or even full system compromise. Staying informed about CVEs affecting DNS servers, applying patches quickly, and hardening your infrastructure can make all the difference.