Cloudflare outage on December 5, 2025 (blog.cloudflare.com)

Article summary

Cloudflare experienced a 25-minute outage on December 5, 2025, affecting approximately 28% of its HTTP traffic. The issue was caused by a change to the company's Web Application Firewall (WAF) that triggered a bug in the rules module, resulting in HTTP 500 errors. The problem was resolved after the change was reverted. The outage was not caused by a cyber attack, but rather by an internal configuration change.

Main themes

• Cloudflare Outage
• Web Application Firewall
• Configuration Change
• Network Reliability
• Error Handling

What commenters say

• The outage highlights the importance of thorough testing before deploying changes to critical infrastructure.
• Some argue that a 30-minute downtime is not a significant issue, while others believe it is unacceptable for a company of Cloudflare's scale and importance.
• The use of a strongly-typed language like Rust could have prevented the error, but others argue that it is not a guarantee against mistakes.
• Cloudflare's global configuration system, which propagates changes quickly without gradual rollouts, may be a contributing factor to the outage.
• The company's error handling and alert systems have been criticized for being too slow, with some arguing that they should be more responsive to changes in failure rates.
• There are differing opinions on whether Cloudflare's services are 'mission critical' and whether the outage had significant consequences, with some citing examples of critical systems that rely on the company's infrastructure.