Cloudflare Containers: Vulnerability Allowing Reading of Residual Data from Other Tenants via Reused Blocks
1. Overview Article Title : How Cloudflare addressed a cross-tenant data exposure vulnerability in Containers Publisher : Cloudflare Publication Date : 2026-09-24 Source : Cloudflare Related Sources : Accomplish: Escaping the Cloudflare Sandbox , BleepingComputer Related Malware, Threat Groups, CVEs, Products : Cloudflare Containers, Cloudflare Sandboxes, Workers Paid, Linux dm-thin Severity :…
Cloudflare Containers and Sandboxes were found to have a vulnerability that could allow an attacker to read data fragments from other tenants' storage. This occurred when portions of reused blocks remained untouched after new writes, as the blocks had not been zero-initialized. The vulnerability was addressed by Cloudflare, which corrected the source title, distinguished authorized research from malicious theft, and outlined the stages of information exposure along with countermeasures taken.
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