Key Points
- Cloudflare outage began at 11:20 AM UTC (4:50 PM IST) on November 18, 2025
- Caused by “unusual spike in traffic” to Cloudflare services, possible DDoS attack suspected
- Major platforms affected: ChatGPT, X, Claude AI, Uber, Discord, Canva, Letterboxd
- Downdetector itself crashed due to outage, receiving over 11,200 reports at peak
- HTTP 500 errors affected Cloudflare Dashboard, API, and customer websites globally
- Company deployed fixes progressively, WARP and Access services restored first
- Cloudflare provides CDN and DDoS protection to millions of websites worldwide
- Second major infrastructure outage after AWS outage last month
- No confirmed cause yet, investigation into traffic spike ongoing
- Services gradually returning to normal with higher-than-usual error rates during recovery
A catastrophic technical outage at Cloudflare, one of the internet’s most critical infrastructure providers, brought down thousands of websites and online services across the globe on Tuesday, November 18, 2025. The incident exposed the fragility of modern web infrastructure and highlighted how deeply dependent the internet has become on a handful of key service providers.
The outage began at precisely 11:20 AM UTC (4:50 PM IST), when Cloudflare’s systems experienced what the company described as a “spike in unusual traffic” to one of its core services. Within minutes, the disruption cascaded across the internet, affecting major platforms including ChatGPT, X (formerly Twitter), Claude AI, Uber, Discord, Canva, and countless other websites that rely on Cloudflare’s content delivery network (CDN) and security services.
Cloudflare’s official statement acknowledged the severity of the situation: “We saw a spike in unusual traffic to one of Cloudflare’s services beginning at 11:20 UTC. That caused some traffic passing through Cloudflare’s network to experience errors. We do not yet know the cause of the spike in unusual traffic”.
The Ironic Downfall of Downdetector
In a twist of irony that highlighted the outage’s severity, Downdetector, the popular platform users turn to for reporting and tracking internet service disruptions, itself went offline during the incident. The failure of Downdetector signaled just how widespread and serious the Cloudflare outage had become, as the monitoring service also relies on Cloudflare’s infrastructure.
At the peak of the crisis, Downdetector had received 11,201 reports of Cloudflare issues at 11:37 AM GMT before it too succumbed to the outage. By 12:45 PM GMT, as services began recovering, reports had decreased to approximately 6,570, suggesting the fix was propagating across the global network.
Major Platforms and Services Brought to Their Knees
The ripple effects of Cloudflare’s failure touched virtually every corner of the internet. OpenAI confirmed that ChatGPT was experiencing “intermittent access issues” and issued an update on its status page stating the incident was “caused by an issue with one of our third-party service providers,” clearly referring to Cloudflare without naming it directly.
X (formerly Twitter) experienced repeated outages throughout the incident, with users receiving HTTP 500 error messages when attempting to access the platform. The error code indicated server-level problems occurring within Cloudflare’s infrastructure rather than issues with X’s own servers or users’ internet connections.
Claude AI, Anthropic’s competing artificial intelligence chatbot, suffered a major outage directly attributed to Cloudflare’s problems. Other high-profile casualties included ride-sharing service Uber, communication platform Discord, online design suite Canva, film review website Letterboxd, news technology websites The Register, Notebookcheck, and Videocardz, and even 3D printing community sites Printables and Thangs.
The popular free MMORPG RuneScape was also impacted, with players turning to Reddit to report they could not log in or access the game’s wiki. Even VPN service Windscribe appeared to be affected, though confirmation was difficult because its status page was also down.
Suspected DDoS Attack: The ‘Unusual Traffic’ Mystery
While Cloudflare has not officially confirmed the cause of the “unusual traffic spike,” cybersecurity experts and industry observers immediately suspected a distributed denial-of-service (DDoS) attack. The company’s language, describing the traffic as “unusual,” suggests it was not normal user activity but potentially malicious in nature.
Cloudflare has extensive experience defending against massive DDoS attacks. Just two months prior to this incident, the company successfully blocked a record-setting 11.5 terabits per second (Tbps) DDoS attack, which itself came shortly after blocking the previous record holder. The company’s infrastructure is specifically designed to absorb and mitigate such attacks, making this outage particularly concerning.
The fact that such a sophisticated defensive system could be overwhelmed or disrupted raises questions about whether this represented a new attack vector or an unprecedented scale of traffic. Cloudflare stated it would conduct a thorough post-incident analysis and publish findings on its blog once the immediate crisis was resolved.
Progressive Recovery: WARP and Access Services Restored First
Cloudflare’s engineering teams worked urgently to restore services, deploying fixes progressively across their global network. At 13:13 UTC (6:43 PM IST), the company reported a significant milestone: “We have made changes that have allowed Cloudflare Access and WARP to recover. Error levels for Access and WARP users have returned to pre-incident rates”.
WARP, Cloudflare’s internet connection security tool that encrypts traffic from users’ devices, had been deliberately disabled in London during remediation attempts. Users in London attempting to access the internet via WARP experienced connection failures during this period, but service was subsequently restored.
By 13:35 UTC (7:05 PM IST), Cloudflare provided another update: “We are continuing to work on restoring service for application services customers.” This indicated that while WARP and Access had recovered, broader services for Cloudflare’s business customers were still experiencing issues.
What Is Cloudflare and Why Does It Matter?
Cloudflare serves as a critical backbone of the modern internet, providing content delivery network (CDN) services, DDoS protection, and security features to millions of websites worldwide. When you visit a website protected by Cloudflare, your connection passes through Cloudflare’s global network before reaching the actual website server. This provides faster loading times, protection from cyberattacks, and improved reliability under normal circumstances.
However, this centralized model also creates a single point of failure. When Cloudflare experiences problems, all websites and services relying on its infrastructure become inaccessible simultaneously, as demonstrated by Tuesday’s incident. The concentration of so much internet traffic through a small number of infrastructure providers has long concerned internet architecture experts.
Second Major Infrastructure Failure in Recent Months
The Cloudflare outage represents the second major internet infrastructure failure in recent months, following a significant Amazon Web Services (AWS) outage last month. These recurring incidents underscore the vulnerability of modern internet architecture, which relies heavily on a small number of massive service providers.
This centralization occurred gradually as companies sought to outsource technical infrastructure to specialized providers rather than managing their own servers and security. While this approach offers advantages in terms of cost, expertise, and scale, it also creates systemic risk when these providers experience technical problems.
Global Impact: Users and Businesses Left Stranded
The timing of the outage, occurring during business hours in Europe and the morning in North America, maximized its disruptive impact. Businesses relying on affected platforms for customer service, e-commerce, or internal communications found themselves unable to operate. Content creators, developers, and remote workers who depend on ChatGPT and similar AI tools for productivity were left unable to access these services.
Users in multiple countries reported frustration on social media (on platforms still functioning), expressing concern about the increasing frequency of major internet outages and the lack of redundancy in critical infrastructure. The incident highlighted humanity’s growing dependence on digital services and the real-world consequences when those services fail.
Investigation Continues: Root Cause Still Unknown
As of the latest updates, Cloudflare had not definitively identified the root cause of the unusual traffic spike that triggered the outage. The company is committed to conducting a comprehensive post-incident analysis and publishing detailed findings once the investigation concludes.
Cloudflare’s statement emphasized their commitment to transparency: “After [restoring service], we will turn our attention to investigating the cause of the unusual spike in traffic. We will post updates to cloudflarestatus.com and more in-depth analysis when it is ready to blog.cloudflare.com.
Lessons for Internet Resilience
This incident reignites long-standing debates about internet architecture and the wisdom of concentrating so much traffic through a handful of infrastructure providers. The old adage “Don’t put all your eggs in one basket” was repeatedly cited by technology journalists covering the outage, as the Cloudflare failure demonstrated the risks of over-reliance on a single provider.
Some cybersecurity experts and internet architects have long advocated for a more decentralized internet infrastructure that would be more resilient to such single points of failure. However, the economic and technical advantages of centralized solutions like Cloudflare have proven difficult to resist for most organizations.
As internet services become increasingly critical to modern life, from healthcare to education to commerce, the need for more robust and resilient infrastructure becomes ever more apparent. Whether this incident will catalyze meaningful changes in how the internet’s foundational infrastructure is architected remains to be seen.
