Red Hat Security Advisory: python-urllib3 security update
Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems. Security Fix(es): * urllib3: urllib3: Unbounded decompression chain leads to resource exhaustion (CVE-2025-66418) * urllib3: urllib3 Streaming API improperly handles highly compressed data (CVE-2025-66471) * urllib3: urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API) (CVE-2026-21441) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
AI Analysis
Technical Summary
This advisory covers three vulnerabilities in the python-urllib3 package: CVE-2025-66418 describes an unbounded decompression chain that can cause resource exhaustion; CVE-2025-66471 involves improper handling of highly compressed data in the streaming API; and CVE-2026-21441 details a decompression-bomb safeguard bypass when following HTTP redirects in the streaming API. These vulnerabilities affect python-urllib3 versions prior to 1.26.5 in Red Hat Enterprise Linux 9.6 Extended Update Support. Red Hat has issued patches to fix these issues in python-urllib3 version 1.26.5-6.el9_6.1.
Potential Impact
The vulnerabilities can lead to resource exhaustion due to unbounded decompression chains and allow bypassing decompression-bomb safeguards, potentially causing denial of service or degraded performance in applications using the affected urllib3 versions. Improper handling of highly compressed data may also affect the stability and reliability of HTTP streaming operations.
Mitigation Recommendations
Red Hat has released an official security update for python-urllib3 in Red Hat Enterprise Linux 9.6 Extended Update Support. Users should apply the updated package python-urllib3-1.26.5-6.el9_6.1 or later to remediate these vulnerabilities. Detailed update instructions are available at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the official patch.
Red Hat Security Advisory: python-urllib3 security update
Description
Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems. Security Fix(es): * urllib3: urllib3: Unbounded decompression chain leads to resource exhaustion (CVE-2025-66418) * urllib3: urllib3 Streaming API improperly handles highly compressed data (CVE-2025-66471) * urllib3: urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API) (CVE-2026-21441) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This advisory covers three vulnerabilities in the python-urllib3 package: CVE-2025-66418 describes an unbounded decompression chain that can cause resource exhaustion; CVE-2025-66471 involves improper handling of highly compressed data in the streaming API; and CVE-2026-21441 details a decompression-bomb safeguard bypass when following HTTP redirects in the streaming API. These vulnerabilities affect python-urllib3 versions prior to 1.26.5 in Red Hat Enterprise Linux 9.6 Extended Update Support. Red Hat has issued patches to fix these issues in python-urllib3 version 1.26.5-6.el9_6.1.
Potential Impact
The vulnerabilities can lead to resource exhaustion due to unbounded decompression chains and allow bypassing decompression-bomb safeguards, potentially causing denial of service or degraded performance in applications using the affected urllib3 versions. Improper handling of highly compressed data may also affect the stability and reliability of HTTP streaming operations.
Mitigation Recommendations
Red Hat has released an official security update for python-urllib3 in Red Hat Enterprise Linux 9.6 Extended Update Support. Users should apply the updated package python-urllib3-1.26.5-6.el9_6.1 or later to remediate these vulnerabilities. Detailed update instructions are available at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the official patch.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2026:1729
- Cve Count
- 3
- Additional Cves
- ["CVE-2025-66471","CVE-2026-21441"]
Threat ID: 6a160973e29bf47b5063be8f
Added to database: 05/26/2026, 20:58:27 UTC
Last enriched: 08/10/2026, 17:48:35 UTC
Last updated: 09/10/2026, 19:36:51 UTC
Views: 101
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