Ever seen one of these?

If you have, you most likely hit the back button instantly. Most people see the red triangle and assume the site they’re visiting has a security problem. They won’t want to risk losing their credit card details and personal information to malicious actors, so they’ll leave, and faced with the same thing, your customers are likely to do the same. If you don’t secure SSL certificates on your websites or have an expired SSL certificate, visitors may look for a competitor that doesn’t show that message.

Not only that, but an expired certificate will also degrade your search engine rankings and could mean that you fail regulatory requirements if you operate in certain industries like health or finance.

 Beyond losing customer trust and search engine ranking drops, expired SSL certificates can open the door to serious security vulnerabilities. For instance, malicious actors can exploit these lapses to conduct man-in-the-middle (MITM) attacks, eavesdropping on and potentially manipulating the data exchanged between your website and its visitors. Furthermore, outdated or expired SSL/TLS protocols can be susceptible to known attacks like POODLE, BEAST, and CRIME, putting sensitive user information at risk. 

Expired SSL certificates can lead to non-compliance with industry regulations (e.g., in healthcare and finance), potentially resulting in fines and damage to your business reputation.

What is an SSL Certificate?

An SSL (Secure Sockets Layer) certificate is a data file hosted on a website’s origin server. It authenticates a website’s identity and enables an encrypted connection between a web server and a browser. It verifies that a server belongs to whom it claims to, which prevents impersonation attacks. It establishes an encrypted connection that protects sensitive information like login credentials, credit card numbers, and personal data, so bad actors can’t snag them.

When you visit an HTTPS website, your browser and the server perform a “handshake” (a quick security check between the two) where they agree on encryption parameters and verify the certificate’s validity. This creates a secure tunnel for data transmission that protects all the data in transit against eavesdropping and tampering, and the browser verifies the certificate’s chain of trust and its revocation status.

Modern websites now use TLS (Transport Layer Security) rather than the older SSL protocol, but the term “SSL certificate” is used to mean both.

Who sets secure SSL standards?

The Certificate Authority/Browser Forum is a voluntary group made up of Certificate Authorities (CAs), web browser vendors, and other stakeholders. It sets standards and addresses emerging threats by updating protocols, phasing out insecure practices (e.g., SHA-1), and promoting modern standards like TLS 1.3.

Before 2015, the secure SSL certificate limit was five years, then three years from 2015 to 2018, and two years from 2018 to 2020. The current maximum is 397 days, and Google seems keen on a 90-day limit, while Apple has suggested reducing it to 47 days by 2028.

Some big-name SSL expiry incidents

Here are some examples of what can go wrong when businesses fail to manage their SSL certificate lifecycles:

Equifax – 2017

Alongside an unpatched remote code execution vulnerability, 79 expired SSL certificates on domain monitoring devices allowed attackers to steal data undetected for 10 months. It faced $1.4 billion in remediation costs, including legal settlements, fines, and security upgrades, and the company’s stock dropped 33%.

O2 (Telefonica UK) – 2018 

Caused a nationwide outage of the O2 mobile network, affecting 32 million users across the UK. The disruption lasted several hours, costing an estimated $100 million and impacting services like 4G and SMS.

LinkedIn – 2017, 2019 

Millions of users were unable to log in, causing disruption.

Spotify – 2020, 2022 

Users couldn’t access the music streaming service for hours, causing widespread complaints on social media and major disruption to producers on the platform.

Microsoft (WinGet) – 2021 

Microsoft’s open-source Windows package manager (WinGet) failed, with users reporting “InternetOpenUrl() failed” errors when installing or updating apps. Users shared error screenshots on GitHub and questioned the company’s reliability.

Amazon Web Services (AWS) – December 7, 2021 

An expired SSL certificate contributed to a significant AWS outage in the US-East-1 region, disrupting services like Amazon’s delivery operations, third-party sellers, and AWS-powered software. The outage delayed exams at colleges and affected businesses like Whole Foods and Amazon Flex, causing financial losses during the holiday season.

Let’s Encrypt (Root Certificate) – September 2021 

Let’s Encrypt’s DST Root CA X3 certificate expired, causing widespread outages for websites and apps relying on its certificates, including Shopify and Fortinet. Devices and systems that hadn’t updated to newer root certificates failed to establish secure connections, leading to errors and downtime.

Megaphone (Spotify Podcast Platform) – 2022 

Listeners were prevented from accessing or downloading content. The outage affected multiple publishers and demonstrated the cascading impact of certificate issues on interconnected services.

Microsoft (Azure, Teams, Outlook) – July 2023

Azure, Teams, Outlook, and SharePoint were down for about 90 minutes globally. The issue caused connectivity problems. 

The benefits of secure SSL certificates

Certificates have a limited lifespan to help organisations avoid these kinds of horror stories. SSL expiry:

• Limits Exposure of Compromised Certificates: Expiry reduces the time a compromised certificate (e.g., stolen private key) can be exploited by malicious actors, minimizing the window for attacks like impersonation or data interception.
• Encourages Adoption of Updated Standards: Regular renewal forces organizations to update to modern encryption protocols (e.g., TLS 1.3), stronger algorithms, and longer key lengths, and phase out obsolete or vulnerable configurations.
• Ensures Re-Verification of Domain Ownership: Periodic expiry requires certificate holders to re-verify their domain and organization with the Certificate Authority (CA), ensuring the legitimate owner retains control and preventing hijacking.
• Acts as a Failsafe for Revocation: While revocation mechanisms like OCSP and CRLs exist, they aren’t foolproof. Expiry ensures that even if a compromised certificate isn’t revoked, it won’t remain valid indefinitely.
• Promotes Active Security Management: Expiry encourages organizations to maintain proactive certificate lifecycle management, fostering a culture of regular security audits and infrastructure updates.
• Reduces Long-Term Risks: Shorter validity periods (e.g., 397 days or 90 days with Let’s Encrypt) align with evolving threats, ensuring certificates don’t outlive their cryptographic reliability as computing power increases.

Automated SSL tools

Manual certificate renewal processes are becoming outdated and risky, and organizations sticking with a manual approach will have to devote more time and resources to renew certificates more often. This will greatly increase the risk of an SSL outage from an expired certificate, so automated certificate lifecycle management (CLM) tools are a better bet. Examples include:

• Certbot 
• Let’s Encrypt (with ACME Clients) 
• acme.sh 
• Win-ACME 
• DigiCert CertCentral

Why SSL Certificate Renewals Are Often Missed

Even with the shortening of SSL certificate lifecycles, manual renewal processes would be challenging for many organizations.

This is often due to:

• Poor communication between teams
• Lack of certificate renewal reminders or lost reminders 
• Budget constraints and limited IT staff 
• Reliance on third-party services with renewal oversights 
• The sheer number of certificates, especially in large organizations with complex web presences, where managing and tracking expirations across numerous domains and subdomains is difficult and error-prone.

These factors increase the risk of overlooked expirations and subsequent security vulnerabilities.

Expired SSL Certificate: Real-world example

Reflectiz alerts for expired SSL certificates, and this example comes from a global ticket retailer. This part tells them that their domain certificate expired at midnight on 4/10/25, and it is a HIGH priority alert for the retailer’s domain. Last detected shows the date of the most recent alert, and Status tells us that it’s new. Category indicates that this is a problem with the domain. The page is not loading scripts, and since April 11, it has not had a secure SSL certificate.

It’s generally a good thing that a page with an expired SSL certificate is no longer loading scripts because the connection cannot be securely encrypted, making it vulnerable to attacks like man-in-the-middle. If scripts aren’t loading, there’s a lower risk of malicious code being introduced or data interception, and that’s especially relevant if those scripts handle sensitive information. However, it’s still critical to renew the SSL certificate to restore secure communication and full functionality and to stop customers from seeing the expiry alert.

From the image below, you can see that Reflectiz alerts don’t just tell you what’s wrong; they explain why it’s a problem and what to do to improve browser security. The context tab tells you why visitors will stay away from your site and why the site should only connect to others with a secure SSL certification.

There are more pointers under the AI Suggestions tab. The Note tab gives you space to make notes about your actions, Audit Log retains details of the event for audit purposes, and Reasoning is where the system generates a justification for the alert.

The expiry alert summary below shows location information for the retailer. First Seen and Last Seen are the dates of the earliest and most recent scans by the platform. The domains are listed, and Virus Total shows instances of any virus detections.

Root Domain Info adds more details about website ownership. SSL Security Info tells us that the Reflectiz web risk exposure rating system gave this site an F. This is the lowest score on its A-F scale, which measures organizations against industry peers. That F won’t improve until its SSL certificate is renewed.

Secure SSL is one of the primary website defenses against attacks by malicious actors, and Reflectiz will alert your security teams before expired certificates can cause you problems. 

Expired SSL Certificates: Key Takeaways

Expired SSL/TLS certificates disrupt secure communications, trigger browser security warnings, and increase the risk of MITM and impersonation attacks.

Certificate expiration can lead to non-compliance with industry standards (e.g., PCI-DSS, HIPAA) and negatively impact SEO performance and service availability.

Shortened certificate lifecycles (currently max 397 days, trending toward 90 or fewer) require automated renewal processes to avoid human error and downtime.

Outages caused by certificate expiration (e.g., AWS, Microsoft, Spotify) demonstrate the operational and reputational impact across complex infrastructures.

Automated Certificate Lifecycle Management (CLM) tools (e.g., Certbot, acme.sh, CertCentral) are now a critical part of DevOps and SecOps practices.

Monitoring solutions like Reflectiz provide visibility into certificate status across domains, alerting teams proactively to mitigate exposure and ensure continuous encryption integrity.

Expired SSL Certificates: FAQs

Q: What happens when an SSL certificate expires?

A: When an SSL certificate expires, web browsers display security warnings to visitors, indicating that the connection to the website is not private. This can lead to a loss of customer trust, decreased search engine rankings, and potential legal issues.  

Q: Are expired SSL certificates a security risk?

A: Yes, expired SSL certificates can create security vulnerabilities. They can be exploited by malicious actors for attacks like man-in-the-middle (MITM) attacks, potentially exposing sensitive user data.  

Q: Why are SSL certificates important?

A: SSL certificates authenticate a website’s identity and enable an encrypted connection between the web server and the browser. This protects sensitive information and prevents impersonation.  

Q: Why do SSL certificates expire?

A: SSL certificates have a limited lifespan to reduce the risk of compromised certificates, encourage the adoption of updated security standards, ensure re-verification of domain ownership, and promote active security management.  

Q: What are some common reasons for missed SSL certificate renewals?

A: Common reasons include poor communication between teams, lack of renewal reminders, budget constraints, reliance on third-party services, and the sheer number of certificates to manage.  

Q: How can I prevent expired SSL certificate issues?

A: Automated certificate lifecycle management (CLM) tools and continuous monitoring solutions like Reflectiz can help organizations effectively manage their SSL certificates and prevent expirations.  

Protect your website and your customers from the dangers of expired SSL certificates. Contact us today to learn how Reflectiz can help.