What are the technical details behind the Cloudflare bug (Cloudbleed)?

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Grade: Education Subject: Support
What are the technical details behind the Cloudflare bug (Cloudbleed)?
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The Cloudflare bug was a buffer overflow vulnerability in Cloudflare's Edge Side Includes (ESI) parser. When processing certain malformed HTML requests, the parser could read beyond the intended memory buffer, returning arbitrary data from Cloudflare's memory alongside the legitimate response. This happened due to incorrect handling of memory allocation and string manipulation.