urllib3 2.6.0-<2.7.0 Decompress Whole Response DoS via Brotli
CVE-2026-44432 Published on May 13, 2026
urllib3: Decompression-bomb safeguards bypassed in parts of the streaming API
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.
Vulnerability Analysis
CVE-2026-44432 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is a Data Amplification Vulnerability?
The software does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output. An example of data amplification is a "decompression bomb," a small ZIP file that can produce a large amount of data when it is decompressed.
CVE-2026-44432 has been classified to as a Data Amplification vulnerability or weakness.
Products Associated with CVE-2026-44432
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Affected Versions
urllib3:- Version >= 2.6.0, < 2.7.0 is affected.
- Version 0:4.6.30-2.el8ap and below * is unaffected.
- Version 0:4.6.30-2.el9ap and below * is unaffected.
- Version 0:2.7.0-1.el9ap and below * is unaffected.
- Version 0:4.7.14-3.el9ap and below * is unaffected.
- Version 0:2.6.3-2.el10_2 and below * is unaffected.
- Version 0:1.26.19-4.el10_2 and below * is unaffected.
- Version 0:1.26.19-3.el8_10 and below * is unaffected.
- Version 0:2.6.3-2.el9_8 and below * is unaffected.
- Version 0:1.26.19-3.el9_8 and below * is unaffected.
- Version 0:1.26.5-8.el9_8 and below * is unaffected.
- Version 1782352950 and below * is unaffected.
- Version 1782352919 and below * is unaffected.
- Version 1782353093 and below * is unaffected.
- Version 1782352847 and below * is unaffected.
- Version 1780356811 and below * is unaffected.
- Version 1780356904 and below * is unaffected.
- Version 1780356941 and below * is unaffected.
- Version 1780356914 and below * is unaffected.
- Version 1784050598 and below * is unaffected.
- Version 1782761510 and below * is unaffected.
- Version 1782650747 and below * is unaffected.
- Version 1783973764 and below * is unaffected.
- Version 1783921549 and below * is unaffected.
- Version 1783923629 and below * is unaffected.
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- Version 1781028735 and below * is unaffected.
- Version 1781102816 and below * is unaffected.
- Version 1779395228 and below * is unaffected.
- Version 1782756541 and below * is unaffected.
- Version 0.69.3-1.2.hum1 and below * is unaffected.
- Version 1.96.0-1.hum1 and below * is unaffected.
- Version 1.2.1-2.hum1 and below * is unaffected.
- Version 2.7.0-3.hum1 and below * is unaffected.
- Version 48.0.0-3.hum1 and below * is unaffected.
- Version 21.1.8-6.hum1 and below * is unaffected.
- Version 2026.5.1-1.hum1 and below * is unaffected.
- Version 2.19.0-1.hum1 and below * is unaffected.
- Version 11.8.8-1.hum1 and below * is unaffected.
- Version 2.48.0-4.1.hum1 and below * is unaffected.
- Version 21.1.8-1.1.hum1 and below * is unaffected.
- Version 1783024305 and below * is unaffected.
- Version 1783701598 and below * is unaffected.
- Version 1783342900 and below * is unaffected.
- Version 1783112979 and below * is unaffected.
- Version 1783091175 and below * is unaffected.
- Version 1783998774 and below * is unaffected.
- Version 1783998857 and below * is unaffected.
- Version 1783010225 and below * is unaffected.
- Version 1782917849 and below * is unaffected.
- Version 1782887848 and below * is unaffected.
- Version 1782854229 and below * is unaffected.
- Version 1782471555 and below * is unaffected.
- Version 1782471579 and below * is unaffected.
- Version 1783073038 and below * is unaffected.
- Version 1782991170 and below * is unaffected.
- Version 1782471656 and below * is unaffected.
- Version 1782471663 and below * is unaffected.
- Version 1783069204 and below * is unaffected.
- Version 1782991170 and below * is unaffected.
- Version 1782472374 and below * is unaffected.
- Version 1782487717 and below * is unaffected.
- Version 1781937357 and below * is unaffected.
- Version 1783955846 and below * is unaffected.
- Version 1781878070 and below * is unaffected.
- Version 1779792651 and below * is unaffected.
- Version 1779711334 and below * is unaffected.
- Version 1782739344 and below * is unaffected.
- Version 1782139619 and below * is unaffected.
- Version 1780393451 and below * is unaffected.
- Version 1782380482 and below * is unaffected.
- Version 1782448455 and below * is unaffected.
- Version 1780560117 and below * is unaffected.
- Version 1780914886 and below * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.