21CTO

Oct 20, 2026 · Information Security

Cloudflare Fixes Cross-Tenant Data Leak in Containers via Storage Allocator Flaw

Cloudflare disclosed and fixed a cross-tenant data leak in its container platform where the dm-thin storage allocator's skip_block_zeroing setting allowed new containers to read residual data from deleted containers, including databases and credentials, across 18 of 24 deployments and 20 of 22 nodes; the fix involved removing the flag, draining hosts, and clearing caches.