Top 10 Common Cybersecurity Vulnerabilities in 2025

Cybersecurity isn’t just an IT problem anymore—it’s a business-critical issue that keeps executives up at night. And for good reason. The threat landscape has become increasingly sophisticated, with attackers constantly finding new ways to exploit cybersecurity vulnerabilities and other weaknesses in our digital infrastructure.

Every day, organizations face a barrage of cyber security threats ranging from ransomware attacks that can shut down entire operations to data breaches that expose sensitive customer information. The cost of these attacks continues to climb, with the average data breach now costing organizations millions of dollars in direct costs, regulatory fines, and lost business.

What makes this particularly challenging is that cybercriminals don’t need to be incredibly sophisticated to cause significant damage. Many successful attacks exploit basic cyber security threats and vulnerabilities that organizations have overlooked or postponed addressing. These security vulnerabilities often exist in the foundational systems that businesses rely on daily—the very infrastructure that keeps operations running smoothly.

The importance of understanding common cybersecurity vulnerabilities

Understanding the most common IT security threats and vulnerabilities that penetration testers encounter provides valuable insight into where organizations are most at risk. These aren’t theoretical threats—they’re real-world attack vectors that cybercriminals actively exploit every day. By examining these patterns, we can better understand how to prioritize security efforts and resources where they’ll have the most impact. This knowledge forms the foundation of any effective cybersecurity strategy, helping organizations move from reactive incident response to proactive threat prevention.

So, let’s dive into the top 10 cyber security vulnerabilities that penetration testers encountered most frequently in 2024 and 2025. More importantly, let’s talk about what you can do to protect your organization from becoming the next headline.

1. Multicast DNS Spoofing / mDNS Spoofing

Here’s something that might surprise you: one of the most common cybersecurity vulnerabilities has nothing to do with sophisticated malware or zero-day exploits. It’s actually about how devices on your network introduce themselves to each other.

Multicast DNS is a system that helps devices on a local network (like your office Wi-Fi) find and connect to each other without needing a central server. Think of it as a local phone book that devices use to locate printers, shared folders, or other network resources.

Attackers can impersonate legitimate devices by responding to these network queries with false information. It’s like someone intercepting a question about “Where’s the printer?” and responding with “It’s over here!” when they’re actually directing you to a malicious device.

This can lead to man-in-the-middle attacks where cybercriminals intercept your communications, steal data, or capture login credentials without your knowledge.

To protect yourself, disable mDNS when it’s not needed, especially in business environments. IT administrators can use Group Policy settings on Windows systems to turn off “Multicast Name Resolution” and implement secure DNS protocols like DNSSEC with proper authentication.

2. NetBIOS Name Service (NBNS) Spoofing

NetBIOS Name Service is a legacy protocol used in Windows networks to resolve domain names in a local network. It allows devices to identify and communicate with each other using names instead of IPs. NetBIOS operates when other name resolution methods like DNS are unavailable, unresponsive, or not configured.

The system first looks for DNS name-to-IP mappings in its local host file. If none are found, it queries the configured DNS servers. If those also fail to resolve the name, it broadcasts an NBNS query to the local network, requesting a response from other devices.

This legacy system has no built-in security checks, making it easy for attackers to redirect your network traffic to malicious devices, potentially stealing sensitive information or login credentials.

To mitigate NetBIOS Name Service spoofing, disable NetBIOS if it’s not required. This can be done via DHCP settings, network adapter configuration, or system registry changes. Additionally, monitor network traffic for suspicious NBNS activity to detect potential spoofing attempts. Modern networks typically don’t require this older protocol.

3. Link Local Multicast Name Resolution (LLMNR) Spoofing

Link-Local Multicast Name Resolution (LLMNR) is a protocol that allows devices on the same local network to resolve hostnames without a DNS server. It uses multicast messages to query and respond to name resolution requests. LLMNR is mainly used in small or ad-hoc networks for easy device discovery.

The system first checks its local host file for a matching DNS name and IP address. If not found, it queries the configured DNS servers for the address. If the DNS servers cannot resolve it, the system broadcasts an LLMNR request on the local network to get help from other devices.

Similar to the previous cybersecurity vulnerabilities, attackers can respond to these network queries with false information, tricking devices into connecting to malicious systems instead of legitimate ones. Cybercriminals can capture authentication attempts and potentially crack passwords or gain unauthorized access to network resources.

To mitigate LLMNR spoofing, Disable LLMNR through Group Policy settings or registry modifications. IT administrators should enable the “Turn Off Multicast Name Resolution” setting to prevent these spoofed responses. These changes help prevent spoofed name resolution responses on the local network.

4. IPV6 DNS Spoofing

IPv6 was supposed to solve many of the Internet’s problems, and in many ways, it has. But it also introduced new attack vectors, particularly around DNS spoofing.

IPv6 DNS spoofing is an attack where a malicious actor intercepts or forges DNS responses over an IPv6 network, manipulating a device into resolving a domain name to a fake or malicious IP address. What makes this particularly dangerous is that IPv6 is often enabled by default on modern systems, but many organizations haven’t properly configured their IPv6 security settings. This can lead to redirection to phishing sites, man-in-the-middle attacks, or unauthorized access. The attack often exploits cybersecurity vulnerabilities in DNS configuration.

To protect against IPv6 DNS spoofing, use secure DNS protocols like DNSSEC to validate DNS responses. Properly configure IPv6 settings and disable unused features, such as rogue router advertisements. Apply Group Policy to restrict DNS server settings to trusted sources. Implement firewall rules to block unauthorized DNS traffic over IPv6. Regular monitoring of DNS traffic also helps detect and respond to suspicious activity.

5. Outdated Microsoft Windows Systems

Outdated Windows systems are highly vulnerable to cyberattacks because they lack security patches for known cybersecurity vulnerabilities. These security flaws can be exploited by attackers to gain unauthorized access, execute malicious code, or spread malware. These systems often lack the latest protections against ransomware, zero-day exploits, and network-based attacks. Without regular updates, they are incompatible with newer security standards and protocols. Additionally, unsupported systems no longer receive security updates from Microsoft, increasing long-term risk.

In order to reduce cybersecurity vulnerabilities in obsolete Microsoft Windows systems, it is recommended that you either upgrade to a supported version of Windows or consistently implement security updates and patches. Implement network segmentation and limit access to critical systems. Use endpoint protection and monitor for unusual activity to reduce exposure to threats.

6. IPMI Authentication Bypass

IPMI (Intelligent Platform Management Interface) is a system that allows IT administrators to remotely manage and monitor servers, even when they’re powered off. IPMI Authentication Bypass is a vulnerability in the Intelligent Platform Management Interface (IPMI) that allows attackers to gain unauthorized access to a server’s management interface without valid credentials remotely. It typically exploits flaws in how IPMI handles authentication or session management. Once bypassed this can lead to the retrieval of password hashes, and if weak or default hashing algorithms are used, attackers may be able to crack them and obtain the clear-text passwords.

To mitigate IPMI Authentication Bypass, disable IPMI if not required or restrict its access to trusted management networks only. Always change default credentials and use strong, complex passwords. Update firmware regularly to patch known cybersecurity vulnerabilities. Additionally, monitor and log IPMI access to detect any unauthorized activity.

7. Windows RCE (EternalBlue)

EternalBlue, a Windows RCE (Remote Code Execution) vulnerability, exploits a flaw in the SMBv1 file-sharing protocol, enabling attackers to execute arbitrary code remotely. This vulnerability was famously used in major cyberattacks like WannaCry and NotPetya, which spread rapidly across networks worldwide, causing billions in damages. The vulnerability (CVE-2017-0144) affects unpatched Windows systems and allows full system compromise without user interaction.

To mitigate the EternalBlue (Windows RCE) vulnerability, apply Microsoft security patches on all affected systems. Disable SMBv1 protocol if it is not required in your environment. Additionally, use network firewalls and segmentations to block SMB traffic from untrusted sources.

8. Windows RCE (Bluekeep)

The Windows RCE vulnerability known as BlueKeep (CVE-2019-0708) affects the Remote Desktop Services on older Windows versions, allowing attackers to execute code remotely without authentication. This vulnerability can be exploited to create wormable attacks that spread malware across networks of vulnerable systems automatically. Attackers can gain complete control of systems with exposed Remote Desktop services, potentially affecting multiple computers in a network without user interaction.

To mitigate the BlueKeep (Windows RCE) vulnerability, apply official Microsoft security patches, disable Remote Desktop Services if not needed, ensure regular system updates, and avoid exposing Remote Desktop to the internet.

9. Firebird Servers Accept Default Credentials

Firebird is a database server that, like many systems, comes with default usernames and passwords (typically SYSDBA/masterkey) that administrators should change during setup. The Firebird Servers Accept Default Credentials vulnerability occurs when the database server is left with its default username and password, allowing unauthorized access. Attackers can exploit this to gain full control over the database. This poses a serious risk, especially if the server is exposed to the internet or untrusted networks. Attackers can gain full control over databases containing sensitive information, potentially accessing, modifying, or stealing critical business data.

To protect yourself, immediately change the default credentials to a strong, unique password, limit access to the Firebird server by restricting it to trusted networks and users, regularly review configurations, and apply security patches to reduce exposure to unauthorized access.

10. Active Directory Certificate Services Privilege Escalation Vulnerabilities

Active Directory Certificate Services (AD CS) manages digital certificates in Windows environments. These certificates are used to verify identities and secure communications. Active Directory Certificate Services (AD CS) privilege escalation vulnerabilities allow attackers to exploit misconfigured certificate templates or permissions to escalate privileges within a domain. These flaws can enable low-privileged users to impersonate higher-privileged accounts, including domain administrators.

This vulnerability can allow low-level users to gain complete control over an organization’s Windows domain, accessing all systems and sensitive information.

To address AD CS ESC vulnerabilities, organizations should apply all relevant Microsoft security patches without delay and regularly review and correct permissions on AD CS registry keys. Strengthening defenses also involves enforcing least privilege access, restricting sensitive resource access, and implementing strong monitoring for unusual activities.

Conclusion

These top 10 vulnerabilities represent the most common security weaknesses found in real-world penetration tests during 2024. While the technical details may seem complex, the solutions often involve fundamental security practices: keeping systems updated, changing default passwords, disabling unnecessary services, and implementing proper monitoring.

The key takeaway for organizations is that many of these vulnerabilities are preventable through good security hygiene and regular maintenance. By understanding these common threats and implementing the recommended protections, businesses can significantly reduce their risk of falling victim to cyberattacks.

Remember, cybersecurity is an ongoing process, not a one-time fix. Regular security assessments, employee training, and staying informed about emerging threats are essential components of a comprehensive security strategy.