← Saturday, September 26, 2026SecurityVulnerability
Cloudflare Containers exposed residual disk blocks across tenants
Researchers showed that a customer could recover residual disk blocks previously used by Containers on the same host, though they could not target a specific customer or workload. The fleet-wide fix and constrained exposure make this a useful case in multi-tenant isolation.
- What
- - A Cloudflare Containers vulnerability let a Workers Paid customer recover residual disk blocks from containers previously run on the same host.
- How
- - With dm-thin block zeroing disabled, a 4 KiB write to a reassigned 64 KiB block could leave the remaining bytes readable.
- Why it matters
- - The issue highlights the risk of reusing storage across tenants without clearing it; Cloudflare says it fixed the fleet and found no evidence of customer compromise.
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