Browser Run: now running on Cloudflare Containers, it’s faster and more scalable

Cloudflare1d ago

When "idle" isn't idle: how a Linux kernel optimization became a QUIC bug

Engineers at Cloudflare discovered a bug in the Linux kernel's CUBIC congestion control algorithm that prevents it from recovering from a congestion collapse event. The issue arises when the congestion window (cwnd) gets permanently pinned at its minimum after a loss event, causing the algorithm to oscillate between recovery and congestion avoidance states. This bug was found in the context of QUIC, where it fails 61% of the time in a test scenario involving heavy loss in the early connection phase.

NetworkingSecurity

1 min

Browser Run: now running on Cloudflare Containers, it’s faster and more scalable

When "idle" isn't idle: how a Linux kernel optimization became a QUIC bug

Building for the future