AIKIDO-2026-997635
urllib3 is vulnerable to Denial of Service (DoS)
69
Medium Risk
This Affects:
urllib3TL;DR
urllib3's chunked Deflate decoding path re-invokes the zlib decompressor without confirming that each call advances the decode state. A chunked response with Deflate content-encoding can be shaped so the decompressor keeps returning without producing output or reaching the end of the stream. Streaming that response causes HTTPResponse.stream() and read_chunked() to loop indefinitely, blocking the calling thread until it is killed externally. The fix detects the stalled decode state and raises a decoding error instead of looping.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and you stream a chunked response with Deflate content-encoding from a server or proxy you do not fully control.
Background info
urllib3 is vulnerable to Denial of Service (DoS) in versions 2.6.2 - 2.7.0.
How to fix this
Upgrade the urllib3 library to the patch version.
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SOC 2Compliant
ISO 27001CompliantISO 42001Compliant
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