Date of incident: November 18, 2025
Affected entity: Cloudflare (global CDN, DNS, security, and application-delivery network)
Summary:
On November 18, 2025, Cloudflare experienced a major global outage that disrupted access to a wide range of online services, including ChatGPT and X (formerly Twitter). The outage produced widespread 500 Internal Server Errors across regions. According to Cloudflare’s official statement, the disruption was triggered by a bug in the generation logic of a Bot Management feature file, which propagated across multiple Cloudflare services and caused instability at the edge. The incident underscored the Internet’s heavy reliance on Cloudflare as a single-provider backbone for DNS, CDN, and WAF services.
What Happened
- Early on November 18, Cloudflare services began returning 500 errors, causing global accessibility failures across major websites and applications.
- Cloudflare later confirmed that the outage was caused by a faulty bot-management configuration file that triggered systemwide degradation.
- Reuters reported that Cloudflare observed a “spike in unusual traffic” around the same time the outage began, contributing to the overload of affected systems.
- The cascading effect impacted Cloudflare’s global edge network, leading to widespread connectivity interruptions for millions of users.
Impact
The outage affected a large portion of the global Internet for approximately one hour. Impacted services included:
- ChatGPT, which became inaccessible for large numbers of users worldwide.
- X (Twitter), which experienced major downtime and accessibility failures.
- Numerous other web applications, APIs, and services that rely on Cloudflare’s DNS, CDN, WAF, and application-delivery layers.
Because Cloudflare sits in front of tens of millions of domains, even a brief service fault created global ripple effects.
Cause of the Outage
Cloudflare’s post-incident communication identified the root cause as:
- A bug in a Bot Management feature file
- The bug triggered a flawed configuration generation process
- The bad configuration propagated across Cloudflare services, amplifying impact
- Resulting in widespread 500 Internal Server Errors and service degradation globally
This aligns with external reporting indicating system instability triggered during a period of abnormal traffic patterns.
Response
Cloudflare took the following actions to restore service:
- Identified the faulty configuration and halted propagation
- Rolled back impacted systems and re-established stable versions of the bot-management logic
- Restored normal traffic routing and edge behavior across regions
- Issued a public apology acknowledging the severity of the disruption, stating: “We failed our customers and the broader Internet.”
As of the available reporting, Cloudflare is preparing a more detailed post-mortem.
Significance
This incident highlights several systemic risks:
- Single-provider concentration: reliance on Cloudflare as a core infrastructure provider creates global blast-radius events when failures occur.
- Automation fragility: automated configuration generation can introduce widespread instability when quality controls fail.
- Interdependent web services amplify outages: DNS, CDN, WAF, and API layers all compound when Cloudflare has issues.
- Global resilience requires testing failover in practice, not only on paper.
Organizations that rely on Cloudflare’s stack should consider validating redundancy across DNS providers, CDN/CDR vendors, and API-delivery paths.
Sources:
Reuters — Cloudflare outage disrupts access for ChatGPT and X
https://www.reuters.com/business/elon-musks-x-down-thousands-us-users-downdetector-shows-2025-11-18/
Financial Times — ChatGPT and X hit by Cloudflare outage
https://www.ft.com/content/9898e434-f7ec-4113-915b-fce28f1a9c25
Washington Post — Cloudflare outage briefly disrupts dozens of apps
https://www.washingtonpost.com/business/2025/11/18/cloudflare-outage-error-status/
Tom’s Hardware — Cloudflare CTO apologizes after global outage
https://www.tomshardware.com/service-providers/cloudflare-apologizes-after-outage-takes-major-websites-offline
NY Post — Users report X is down as Cloudflare probes internal server error
https://nypost.com/2025/11/18/business/users-report-x-is-down-as-cloudflare-probes-internal-server-error/
Bild — Cloudflare reports global disruption
https://www.bild.de/leben-wissen/auch-x-und-chatgpt-betroffen-netzwerk-betreiber-cloudflare-meldet-weltweite-stoerung-691c630015479c9d7f9a00d9