httplib2: Decompression Bomb Denial of Service via Unbounded gzip/deflate Response Handling

Summary

The httplib2 HTTP client library performs unbounded decompression of HTTP response bodies encoded with Content-Encoding: gzip or deflate. A malicious or compromised HTTP server can return a small compressed payload (approximately 150 KB) that expands to an arbitrarily large size in memory (150 MB or more), causing MemoryError or OOM-kill in the client process. This is a classic decompression bomb (zip bomb) attack against the HTTP client.

Any application using httplib2.Http().request() against untrusted or attacker-controlled HTTP endpoints is affected.

Details

Affected code: httplib2/__init__.py - _decompressContent() function

The decompression path has two unbounded operations:

gzip decompression (line 394):

content = gzip.GzipFile(fileobj=io.BytesIO(new_content)).read()