Urllib3

5 CVEs product

Monthly

CVE-2026-21441 HIGH PATCH This Week

urllib3 versions 1.22 through 2.6.2 perform unnecessary decompression of redirect response bodies in the streaming API, consuming memory and processing resources before any read methods are invoked. An unauthenticated remote attacker can trigger excessive decompression of large redirect responses to cause denial of service through memory exhaustion or high CPU consumption. This vulnerability affects all Python applications using urllib3's streaming functionality with compressed HTTP redirects.

Python Urllib3 Redhat Suse
NVD GitHub
CVSS 3.1
7.5
EPSS
0.0%
CVE-2025-66471 HIGH PATCH This Week

A security vulnerability in version 1.0 and (CVSS 7.5). High severity vulnerability requiring prompt remediation. Vendor patch is available.

Information Disclosure Python Ubuntu Debian Urllib3 +2
NVD GitHub
CVSS 3.1
7.5
EPSS
0.0%
CVE-2025-66418 HIGH PATCH This Week

urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.

Python Denial Of Service Ubuntu Debian Urllib3 +2
NVD GitHub
CVSS 3.1
7.5
EPSS
0.0%
CVE-2025-50182 MEDIUM PATCH This Month

urllib3 is a user-friendly HTTP client library for Python. Starting in version 2.2.0 and prior to 2.5.0, urllib3 does not control redirects in browsers and Node.js. urllib3 supports being used in a Pyodide runtime utilizing the JavaScript Fetch API or falling back on XMLHttpRequest. This means Python libraries can be used to make HTTP requests from a browser or Node.js. Additionally, urllib3 provides a mechanism to control redirects, but the retries and redirect parameters are ignored with Pyodide; the runtime itself determines redirect behavior. This issue has been patched in version 2.5.0.

Python Node.js Open Redirect Ubuntu Debian +3
NVD GitHub
CVSS 3.1
5.3
EPSS
0.0%
CVE-2025-50181 MEDIUM POC PATCH This Month

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Python Open Redirect SSRF Ubuntu Debian +3
NVD GitHub
CVSS 3.1
5.3
EPSS
0.0%
CVE-2026-21441
EPSS 0% CVSS 7.5
HIGH PATCH This Week

urllib3 versions 1.22 through 2.6.2 perform unnecessary decompression of redirect response bodies in the streaming API, consuming memory and processing resources before any read methods are invoked. An unauthenticated remote attacker can trigger excessive decompression of large redirect responses to cause denial of service through memory exhaustion or high CPU consumption. This vulnerability affects all Python applications using urllib3's streaming functionality with compressed HTTP redirects.

Python Urllib3 Redhat +1
NVD GitHub
CVE-2025-66471
EPSS 0% CVSS 7.5
HIGH PATCH This Week

A security vulnerability in version 1.0 and (CVSS 7.5). High severity vulnerability requiring prompt remediation. Vendor patch is available.

Information Disclosure Python Ubuntu +4
NVD GitHub
CVE-2025-66418
EPSS 0% CVSS 7.5
HIGH PATCH This Week

urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.

Python Denial Of Service Ubuntu +4
NVD GitHub
CVE-2025-50182
EPSS 0% CVSS 5.3
MEDIUM PATCH This Month

urllib3 is a user-friendly HTTP client library for Python. Starting in version 2.2.0 and prior to 2.5.0, urllib3 does not control redirects in browsers and Node.js. urllib3 supports being used in a Pyodide runtime utilizing the JavaScript Fetch API or falling back on XMLHttpRequest. This means Python libraries can be used to make HTTP requests from a browser or Node.js. Additionally, urllib3 provides a mechanism to control redirects, but the retries and redirect parameters are ignored with Pyodide; the runtime itself determines redirect behavior. This issue has been patched in version 2.5.0.

Python Node.js Open Redirect +5
NVD GitHub
CVE-2025-50181
EPSS 0% CVSS 5.3
MEDIUM POC PATCH This Month

urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

Python Open Redirect SSRF +5
NVD GitHub

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