Riskcovery

CVE-2026-44432

urllib3: Decompression-bomb safeguards bypassed in parts of the streaming API

State
Published
Severity
8.9 High
Published
May 13, 2026
Updated
Sep 10, 2026
Reserved
May 6, 2026

Read the record on cve.org

Description

urllib3 is an HTTP client library for Python. From 2.6.0 to before 2.7.0, urllib3 could decompress the whole response instead of the requested portion (1) during the second HTTPResponse.read(amt=N) call when the response was decompressed using the official Brotli library or (2) when HTTPResponse.drain_conn() was called after the response had been read and decompressed partially (compression algorithm did not matter here). These issues could cause urllib3 to fully decode a small amount of highly compressed data in a single operation. This could result in excessive resource consumption (high CPU usage and massive memory allocation for the decompressed data) on the client side. This vulnerability is fixed in 2.7.0.

Scores

CVSSScoreVectorSource
4.08.9 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:HGitHub_M
3.17.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hredhat-SADP

Weaknesses

  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

Affected Products

ProductVersions
urllib3urllib3
  • >= 2.6.0, < 2.7.0Affected

References

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