Red Hat Security Advisory: python3.11-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 python3.11-urllib3 package: CVE-2025-66418 involves an unbounded decompression chain that can cause resource exhaustion; CVE-2025-66471 concerns improper handling of highly compressed data in the streaming API; and CVE-2026-21441 allows bypassing decompression-bomb safeguards when following HTTP redirects in the streaming API. These vulnerabilities could be exploited to exhaust system resources or bypass protections against decompression bombs. The issues are fixed in the updated python3.11-urllib3 package provided for Red Hat Enterprise Linux 9.6 Extended Update Support.
Potential Impact
The vulnerabilities can lead to resource exhaustion due to unbounded decompression chains and improper handling of compressed data, potentially causing denial of service conditions. Additionally, the decompression-bomb safeguard bypass could allow attackers to circumvent protections designed to prevent excessive resource consumption during HTTP redirects. No known exploits in the wild have been reported. The impact is rated as important by Red Hat Product Security.
Mitigation Recommendations
Red Hat has released an updated python3.11-urllib3 package (version 1.26.12-5.el9_6.1) that addresses these vulnerabilities. Users of Red Hat Enterprise Linux 9.6 Extended Update Support should apply this update promptly following Red Hat's guidance at https://access.redhat.com/articles/11258. No alternative mitigations are specified, and the update is the recommended remediation.
Red Hat Security Advisory: python3.11-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
pkg:rpm/redhat/python3.11-urllib3Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This advisory covers three vulnerabilities in the python3.11-urllib3 package: CVE-2025-66418 involves an unbounded decompression chain that can cause resource exhaustion; CVE-2025-66471 concerns improper handling of highly compressed data in the streaming API; and CVE-2026-21441 allows bypassing decompression-bomb safeguards when following HTTP redirects in the streaming API. These vulnerabilities could be exploited to exhaust system resources or bypass protections against decompression bombs. The issues are fixed in the updated python3.11-urllib3 package provided for Red Hat Enterprise Linux 9.6 Extended Update Support.
Potential Impact
The vulnerabilities can lead to resource exhaustion due to unbounded decompression chains and improper handling of compressed data, potentially causing denial of service conditions. Additionally, the decompression-bomb safeguard bypass could allow attackers to circumvent protections designed to prevent excessive resource consumption during HTTP redirects. No known exploits in the wild have been reported. The impact is rated as important by Red Hat Product Security.
Mitigation Recommendations
Red Hat has released an updated python3.11-urllib3 package (version 1.26.12-5.el9_6.1) that addresses these vulnerabilities. Users of Red Hat Enterprise Linux 9.6 Extended Update Support should apply this update promptly following Red Hat's guidance at https://access.redhat.com/articles/11258. No alternative mitigations are specified, and the update is the recommended remediation.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2026:1704
- Cve Count
- 3
- Additional Cves
- ["CVE-2025-66471","CVE-2026-21441"]
Threat ID: 6a16096ce29bf47b50632ab8
Added to database: 05/26/2026, 20:58:20 UTC
Last enriched: 08/10/2026, 17:49:47 UTC
Last updated: 09/10/2026, 19:36:51 UTC
Views: 54
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