Understanding common SSL misconfigurations and how to prevent them

However, not all SSL certificates offer the same level of protection, and their effectiveness depends on how they are obtained, configured, and deployed. Proper SSL/TLS configuration is key for safeguarding sensitive data, maintaining compliance with industry regulations, and ensuring a seamless user experience.

Unfortunately, misconfigurations—such as certificate name mismatch, weak cipher suite selection, or failing to update certificates—can expand the attack surface, leaving organizations vulnerable to data breaches and regulatory penalties. These security gaps can weaken the encryption and authentication that users rely on when accessing websites. Thankfully, adopting best practices in certificate management can mitigate these risks.

Keep reading to learn how to avoid some of the most common SSL certificate misconfigurations.

What are SSL misconfigurations?

SSL misconfigurations occur when certificates are incorrectly implemented or managed. Specifically, any issue that compromises the security or functionality of SSL certificates or the websites they protect can be considered a misconfiguration. These problems can surface before, during or after the SSL/TLS handshake and often appear as SSL/TLS errors.

Why SSL misconfigurations are critical to address

This type of issue must be addressed (and ideally, avoided in the first place) for security purposes. If left unresolved, SSL certificates cannot effectively encrypt websites or authenticate identities, leading to potential outages, downtime, and data breaches, as well as damaging an organization’s reputation..

Misconfigurations also take a financial toll by reducing the return on investment in SSL/TLS certificates. When certificates fail to function properly, the expenses involved in obtaining and deploying them can be wasted, since they aren’t delivering their intended benefits.

Finally, misconfigurations can undermine SEO strategies, albeit in a more limited way. Google does regard HTTPS as a minor ranking signal, outages and configuration errors can still reduce a site’s visibility in search results. Over time, this may affect traffic levels and user trust, further highlighting the importance of proper SSL/TLS management.

Common SSL misconfigurations

Many types of SSL misconfigurations threaten the security of modern websites. These can occur in response to IT mistakes and often relate to manual renewal processes. Common concerns include:

Certificate name mismatch

SSL certificate name mismatches may occur if the domain name in the browser’s address bar fails to match the domain names listed within digital certificates. This, in turn, could lead to browser error messages. Domain changes are sometimes to blame, although mismatches may also exist due to issues with the Common Name (CN) or the Subject Alternative Name (SAN) in the Certificate Signing Request (CSR) or Certificate itself.

Thankfully, this is one of the most easily avoidable concerns: double-check the CN and SAN, along with certificate installation. Automation can limit these problems by limiting the burden on IT staff, who may be more prone to such mistakes if dealing with high volumes of digital certificates manually.

Missing or misconfigured certificate chains

Certificate chains form extended lists of digital certificates and reveal how SSL/TLS certificates are linked to certificate authorities (CAs). These involve hierarchical chains of trust, beginning with root certificates that function as anchors for the entire public key infrastructure (PKI). Stored within highly secure environments — and offering a starting point for verifying all other certificates within this hierarchy — root certificates can be pre-installed to ensure they are trusted by default.

Intermediate certificates (sometimes referred to as Subordinate CA Certificates), occupy the space between root certificates and the end-entity certificates known as leaf certificates. These are important because they limit the need for root CAs to issue end-entity certificates directly, something which is prohibited by the CA/B Forum Guidelines..

These certificate chains can potentially be misconfigured if intermediate certificates are missing. This breaks the certificate chain of trust, prompting validation errors and undermining overall PKI security. This is best avoided by verifying that complete certificate chains are installed, encompassing both root and intermediate certificates, in the correct order.

Weak cipher suites or outdated protocols

Offering instructions for how to secure networks, cipher suites feature series of cryptographic algorithms, including key exchange algorithms (for encrypting and decrypting sensitive information), message authentication code (MAC) algorithms (for conducting data integrity checks), and bulk encryption algorithms (for encrypting data in transit).

Several factors can cause cipher suites to become weak, including outdated encryption algorithms (RC4, 3DES), short key lengths (RSA 1024-bit or weaker), and deprecated hash functions (MD5, SHA-1) that are vulnerable to brute-force attacks and tampering. Likewise, older SSL/TLS protocols such as TLS 1.1 or SSL 3.0 lack modern security protections and remain vulnerable to well-known exploits. To maintain a strong security posture, it is necessary to disable these outdated protocols and replace them with newer, more secure versions.

Improper redirects or mixed content

Redirects help to guide users towards secure websites. Done right, these can overcome the many risks associated with unencrypted connections. HTTP-to-HTTPS redirects, for example, promote access to secure websites. If these are misconfigured, however, users may become vulnerable to SSL stripping attacks, in which websites are downgraded from HTTPS to HTTP. Strict HTTP-to-HTTPS redirect configurations are crucial, with regular auditing providing additional opportunities to eliminate problematic HTTP elements.

Expired or revoked SSL certificates

SSL certificates can become invalid in two main ways: through expiration or revocation. Certificate expiration occurs when digital certificates are not renewed according to established validity periods. A certificate may be revoked, on the other hand, if the CA declares it invalid before it naturally expires—often due to security concerns or policy violations. In both cases, expired or revoked certificates no longer offer promised protection via encryption and authentication. Outages can prompt huge risks but are fully avoidable; certificate lifecycle management (CLM) tools, like Sectigo’s Certificate Manager, track expiration dates, with automated solutions ensuring prompt renewals.

Using a Self-signed SSL certificate

While not technically a misconfiguration, using self-signed SSL certificates can increase the likelihood of misconfigurations and generally does not meet the same cryptographic or trust standards as certificates issued by a reputable CA. Certificate Authorities complete a vetting process to verify that all entities requesting certificates are legitimate, which does not happen when using a self-signed certificate.

Self-signed certificates may seem more cost-effective at first glance, but because they bypass third-party validation, they are more susceptible to man-in-the-middle (MITM) attacks and other cybersecurity risks. These certificates are particularly problematic for public-facing websites and should be avoided whenever possible. It’s best to stick with trusted CAs such as Sectigo.

Consequences of SSL misconfigurations

SSL misconfiguration can spark a wide range of concerns, all of which can be costly on both a short and long-term basis. Potential repercussions include:

Security risks

Put simply, SSL misconfigurations prevent organizations from fully benefiting from the security and trust that properly implemented digital certificates provide. This ultimately makes it easier for hackers to intercept data (as in MITM attacks) or to force users onto unencrypted connections (via SSL stripping).

Likewise, misconfigurations can amplify the risks of certificate spoofing and session hijacking, while outdated algorithms make it even easier for attackers to compromise encryption and access sensitive information.

Compliance issues

SSL/TLS certificates can support compliance efforts, but only if implemented correctly. Misconfigurations may violate strict requirements associated with the Payment Card Industry Data Security Standard (PCI DSS) or the General Data Protection Regulation (GDPR). This can also have industry-specific implications — especially in the healthcare sector, as compliance with the Health Insurance Portability and Accountability Act (HIPAA) plays a critical role in maintaining patient privacy.

Operational downtime

Misconfigurations dramatically increase the potential for certificate expiration and outages, both of which can lead to significant downtime. This can have devastating repercussions, including immediate financial losses along with long-term reputational damage.

Best practices to prevent SSL misconfigurations

The misconfigurations highlighted above are nearly always avoidable. The easiest and most effective strategy for bypassing these issues? Using a trusted CA. Beyond this, several simple, yet impactful solutions can limit misconfiguration while promising many additional improvements in terms of security, compliance, and overall efficiency.

Use automated certificate management

Automated certificate management helps IT teams do more with less. These solutions expedite the otherwise time-consuming processes of manually issuing, renewing, and revoking digital certificates — processes expected to take even more time as 90 or even 47-day validity periods enter the picture. Instead of dedicating extra time to manual certificate renewal, IT experts can focus on resolving security issues and implementing innovative strategies.

Regularly audit SSL/TLS configurations

Audits and assessments are crucial from a compliance standpoint, as these ensure that security solutions are properly implemented and that any potential vulnerabilities within an organization are promptly detected. Sectigo Certificate Manager aids this process by providing automated discovery, monitoring, and auditing of SSL certificates, helping organizations maintain compliance and prevent misconfigurations.

Stay updated with industry standards

Evolving industry standards can have a huge impact on certificate lifecycle management, with crypto agility increasingly needed to ensure that organizations remain up to date. The Certification Authority Browser Forum (CA/Browser Forum) offers valuable guidance, establishing industry-wide rules for publicly trusted certificates.

Taking a closer look at the CA/Browser Forum’s Baseline Requirements (BRs), along with its regular meeting minutes, can provide valuable insights. Meanwhile, resources such as Sectigo's Root Causes podcasts offer easier-to-understand insights regarding the CA/Browser Forum's most important developments.

Train IT teams and developers

The most powerful CLM solution will never live up to its full potential unless it is supported by well-trained IT professionals who understand SSL/TLS best practices. These professionals should fully understand how automated solutions function and how they can work alongside them to improve overall security and compliance. Ongoing training may be necessary as SSL/TLS best practices evolve, as a well-informed workforce ultimately enhances crypto agility.

How Sectigo can help

SSL/TLS certificates are essential for modern web security and compliance—but not all certificates or certificate strategies are created equal. By partnering with a trusted CA like Sectigo, you gain access to industry-leading SSL certificates that provide robust encryption and dedicated support for resolving technical issues.

To further reduce the risk of misconfigurations and simplify certificate operations, consider Sectigo Certificate Manager. With proactive monitoring, full visibility, and automated workflows, SCM helps prevent outages and ensures every certificate remains up to date. Learn more about Sectigo’s SSL certificates or schedule a demo of SCM to see how these solutions can strengthen your overall security.

Related posts:

Preparing for the future: Apple’s 47-Day certificate lifespan proposal

What is a self-signed certificate and how to create one

Certificate Signing Request (CSR) Guide