Somewhere in your organization is a spreadsheet of certificate expiry dates, and someone who owns it. That is not a caricature. DigiCert’s 2026 research with Omdia surveyed more than 400 senior IT leaders and found that 47% still rely on manual tracking methods such as spreadsheets, and only 34% have a complete, current view of what they hold. The spreadsheet works because renewals come around once a year, and one person with a calendar can keep the whole estate in their head.

The industry has decided to take that away. The CA/Browser Forum voted in April 2025 to bring the maximum TLS certificate lifespan down in steps: 200 days from March 2026, 100 days from March 2027, and 47 days from March 2029, with domain validation reuse dropping to 10 days. The first step is already live: since March 15, 2026, no publicly trusted TLS certificate can be valid for more than 200 days. By 2029 you will be proving ownership of your domains roughly every month, for every certificate, forever. The spreadsheet does not survive that. Neither does the person.

Why TLS certificate lifespans are shrinking to 47 days

Shorter lifespans shrink the window in which a stolen key or a mis-issued certificate is useful, and they push the whole ecosystem onto automation, which is where the reliability actually comes from. The destination is better. The journey is where outages live. Every manual step in your renewal process is a place where a 47-day cycle breaks something a 365-day cycle never stressed. We covered what the vote means for Imperva customers when it passed; this post is the checklist.

How to prepare for 47-day certificates: five things to do, in order

  1. Inventory what you actually have. Every certificate, every domain, every site, and who renews it. Cloud WAF reports SSL coverage status for each protected site, so start with your public-facing estate. It is the part with a deadline attached and the part your customers meet first.
  2. Automate domain validation now. Manual validation at a 10-day reuse window is not a process, it is a permanent job for somebody. Automatic CNAME validation makes ownership proof continuous, and it is the single change that turns the 2029 schedule from alarming to routine. The payoff starts now, not in 2029: Imperva already requires domain revalidation every 99 days for its managed certificates. We walked through the setup in Effortless certificate management with automated CNAME validation.
  3. Find your non-SNI traffic before it finds you. Server Name Indication (SNI) is the TLS extension that tells the server which hostname a client is asking for. Clients that do not send it, usually older HTTP libraries, outdated monitoring tools and misconfigured internal services, cannot be served a site certificate (a site with non-SNI connections is not eligible for one), and they are rejected outright once a site moves to SNI-only mode. That is why this step comes before the next one. Non-SNI clients are also invisible unless you go looking. One custom rule with the filter hasSNI == false, set to Alert, logs every non-SNI request as a security event without blocking anything. Leave it running for a week or two, since some of this traffic is periodic, then decide. Imperva Cloud WAF Technical Guide: How to Identify Non-SNI Traffic Before Enabling SNI-Only Mode walks through it step by step.
  4. Isolate the blast radius. A certificate shared across your whole estate means one renewal problem is everyone’s problem. Imperva site certificates give each site its own certificate, its own coverage status and up to 50 domains, so one team’s missed renewal does not become another team’s outage. New SNI-only sites have required site certificates since September 13, 2026, and Imperva recommends migrating existing SNI sites off shared account certificates by December 31, 2026, before automatic migration begins in Q1 2027.
  5. Connect the certificate system you already run. If your certificates are governed in a Certificate Lifecycle Management (CLM) platform, the system that issues, tracks and renews certificates centrally, or in your own PKI, those renewals should reach your WAF without a person in between. The SSL Integration Center connects that workflow directly to Imperva Cloud WAF. DigiCert Trust Lifecycle Manager and Keyfactor Command are on the supported vendor list, with further CLM integrations in progress.

What Imperva is already doing: 90-day certificates and the R46 root

Imperva-managed certificates have already moved to 90-day validity (with domain validation every 99 days), ahead of the industry deadlines, with renewal and deployment automated end to end. Root trust is moving too: the GlobalSign root transition (R3 to R46) is covered by a cross certificate that Imperva includes by default until the R3 root expires in March 2029, so legacy clients keep working, and action is needed only if you pin to a specific root certificate. The direction of travel is simple. Certificate work becomes something you configure once, not something you do monthly.

The detail lives in the Cloud WAF documentation, and walks the site-certificate path step by step.

Back to that spreadsheet. If it is yours, the right time to retire it is while it still works. If you retired it years ago, the question is whether your automation reaches all the way to your applications, or stops at the CA.

Frequently asked questions about 47-day certificates

When do 47-day TLS certificates take effect?
From March 15, 2029, publicly trusted TLS certificates can be valid for no more than 47 days. The CA/Browser Forum schedule gets there in steps: 200 days from March 15, 2026 (already in force) and 100 days from March 15, 2027.

How often will I need to validate domain ownership?
The period for reusing domain validation follows the same schedule: 200 days from March 2026, 100 days from March 2027 and 10 days from March 2029. In practice that means validating for almost every renewal, which is why an automated method such as CNAME delegation matters.

Do I need to do anything for Imperva-managed certificates?
Imperva renews and deploys its managed certificates automatically, and they already have 90-day validity. What stays with you is domain validation (automatic CNAME validation removes it), moving SNI sites from shared account certificates to site certificates, and updating your trust store if you pin to a root certificate.

What happens to clients that don’t support SNI?
A client that doesn’t send SNI can’t be served a site certificate, and once a site moves to SNI-only mode those connections are rejected. A custom rule with the filter hasSNI == false, set to Alert, shows whether you have any before you switch.

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