Loop with Unreachable Exit Condition ('Infinite Loop')

Summary

urllib3 is an HTTP client library for Python. In versions 2.6.2 prior to 2.8.0, `HTTPResponse.stream` and `HTTPResponse.read_chunked` can enter an infinite loop because the Deflate decoder retains trailing bytes as unconsumed input after reaching end-of-stream and repeatedly decodes them without progress. The issue occurs when an untrusted server sends a chunked Deflate response whose decoded body exceeds a positive finite chunk size and whose encoded body has trailing bytes, specifically a response with `Transfer-Encoding: chunked` and `Content-Encoding: deflate`, content decoding enabled, and the positive finite amt=N streaming chunk size. The attack mechanism is that a malicious server returns a compressed chunked response with trailing bytes after the Deflate stream. The impact is excessive CPU usage and a request that does not complete, and network read timeouts do not interrupt the loop because no further socket read occurs. This issue is fixed in version 2.8.0.