The Cloudflare Outage: A Wake-Up Call for Digital Resilience in Construction

On November 18, 2025, a major disruption at Cloudflare, a critical backbone provider for modern internet infrastructure, ripped out across the digital world. They added themselves to a list of global cloud service providers to experience issues within the last couple of months. Services from ChatGPT and X (formerly Twitter) to Canva saw widespread failures or slowed responses. For the public, it was a momentary frustration. For businesses, particularly those in regulated or operationally critical sectors, it served as a sharp reminder: even the most sophisticated cloud security platforms are not immune to failure. In this analysis, we unpack the cause, the impact, and the strategic implications for our sector. 

Understanding the Disruption 

Here is a concise breakdown of the root cause, Cloudflare’s response, and the observed impact.  

The Trigger: A Database Configuration Change 

Cloudflare initiated a change to the permissions within one of its internal database systems (a ClickHouse cluster). This seemingly minor update inadvertently caused a specific internal file, used by Cloudflare’s Bot Management system, to grow significantly beyond its intended size. 

The Failure Point 

This “feature file” contains the traits Cloudflare uses to distinguish between legitimate users and malicious bots. The system designed to read this file had a hard upper limit; it was not engineered to handle the file at double its normal capacity. As these oversized files propagated globally, the systems attempting to process them “panicked” (crashed). 

Propagation and Instability 

Compounding the problem, the corrupted, oversized file was repeatedly regenerated every five minutes across parts of Cloudflare’s database cluster. This resulted in the network oscillating: services would temporarily recover when a correct file version was distributed, only to fail again when the faulty one spread. The initial symptoms were so severe they were briefly mistaken for a Distributed Denial of Service (DDoS) attack. Cloudflare confirmed there was no evidence of malicious activity. 

Fix and Recovery 

Engineers halted the regeneration and propagation of the faulty file. They initiated a rollback to a previously verified good version and forced a restart of their core proxy services. The bulk of core traffic was restored by approximately 14:30 UTC, with full stabilisation across all dependent services achieved by 17:06 UTC. 

Impacted Services 

The outage affected core Cloudflare offerings, including their CDN (Content Delivery Network), security proxy, authentication services (Access), and key value store (Workers KV). Users attempting to reach protected sites saw widespread HTTP 5xx errors (Internal Server Error). Cloudflare publicly stated the incident was “unacceptable” given its central role in the internet ecosystem. 

A Call for Resilience 

The recent outages demand a serious assessment of resilience architecture: 

• Architectural Redundancy: We must assess the viability of implementing defences like dual Content Delivery Network (CDN) providers, more distributed origin hosting, and robust failover mechanisms. 

• Digital Business Continuity: Digital infrastructure resilience must be formally integrated into business continuity planning, receiving the same weight as physical site safety or power backups. 

• Redundant Connectivity: Single points of failure in both LAN and WAN connections should be eliminated and dual carriers or SD-WAN solutions used to provide diverse upstream routes.  

Broader Lessons and Call to Action 

Centralisation Risk: The internet is physically distributed, but its services are centrally concentrated among a few providers. This brings efficiency but creates a single point of failure that impacts entire sectors. How many users would have been calling their IT team raising tickets without knowing that their issue was caused by Cloudflare?  

Engineering Assumptions: The root cause was a broken assumption: “the config file will not grow beyond X.” For any company building or relying on digital platforms, validating fundamental assumptions and building robust guardrails is paramount.  

Transparency and Trust: Cloudflare’s detailed public postmortem is a template for rebuilding trust. Even the largest and most important of companies make mistakes, but how the sector grows from those experiences is key. 

Action Plan for Customers: 

• Review Architecture: Audit the critical digital services that rely on a single cloud or CDN provider. 

• Design Redundancy: Explore and plan for fallback strategies across your network, such as dual CDN and internet connectivity failover. 

• Run Incident Simulations: Conduct a “digital outage tabletop exercise” to stress test your response playbook should core components fail for a few hours. 

• Raise Awareness: Use this incident as a critical learning moment across all business functions (IT, Operations, Leadership) to establish digital resilience as a core business priority.