How Cloudflare addressed a cross-tenant data exposure vulnerability in Containers

Cloudflare disclosed a storage allocation vulnerability in Containers where dm-thin configured with skip_block_zeroing could allow a Workers Paid tenant to recover residual 64 KiB physical blocks (partially overwritten by 4 KiB writes) containing data from prior containers; Cloudflare and the reporting researchers validated the issue, removed skip_block_zeroing, retired affected snapshots and restarted hosts to clear mappings, completed fleet remediation, and reported no evidence of malicious exploitation.