CyberSecBulletin
CVE-2026-44432NVD status: Modified

urllib3: Improper Handling of Highly Compressed Data (Data Amplification)

Published Updated By the CyberSecBulletin desk

CVE-2026-44432 is a high-severity improper handling of highly compressed data (data amplification) vulnerability in urllib3, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected urllib3 versions: >= 2.6.0, < 2.7.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.68% chance of exploitation within 30 days, higher than 53% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of urllib3 you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Urllib3urllib3>= 2.6.0, < 2.7.0Not stated
Red HatRed Hat Ansible Automation Platform 2.5 for RHEL 8Not specified in the recordNot stated
Red HatRed Hat Ansible Automation Platform 2.5 for RHEL 9Not specified in the recordNot stated
Red HatRed Hat Ansible Automation Platform 2.6 for RHEL 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 10Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.4 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.6 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat AI Inference Server 3.3Not specified in the recordNot stated
Red HatRed Hat AI Inference Server 3.4Not specified in the recordNot stated
Red HatRed Hat Ansible Automation Platform 2.5Not specified in the recordNot stated
Red HatRed Hat Ansible Automation Platform 2.6Not specified in the recordNot stated
Red HatRed Hat Ansible Automation Platform 2.7Not specified in the recordNot stated
Red HatRed Hat Discovery 2Not specified in the recordNot stated
Red HatRed Hat Hardened ImagesNot specified in the recordNot stated
Red HatRed Hat Migration Toolkit for Applications 8.2Not specified in the recordNot stated
Red HatRed Hat OpenShift AI 2.25Not specified in the recordNot stated
Red HatRed Hat OpenShift AI 3.3Not specified in the recordNot stated
Red HatRed Hat Quay 3.10Not specified in the recordNot stated
Red HatRed Hat Quay 3.12Not specified in the recordNot stated
Red HatRed Hat Quay 3.15Not specified in the recordNot stated
Red HatRed Hat Quay 3.16Not specified in the recordNot stated
Red HatRed Hat Quay 3.9Not specified in the recordNot stated

Version data comes from the organisation that assigned the CVE; 26 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 4.08.9HighCNA (github.com)
CVSS 3.17.5HighNVD
CVSS 3.17.5HighCNA

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Handling of Highly Compressed Data (Data Amplification)

The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.

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

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in urllib3

All urllib3 vulnerabilities

Recent Improper Handling of Highly Compressed Data (Data Amplification) vulnerabilities

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