CVE-2025-50181

Published Jun 19, 2025

Last updated 3 months ago

CVSS medium 5.3

Overview

Description
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.
Source
security-advisories@github.com
NVD status
Modified
Products
urllib3

Risk scores

CVSS 3.1

Type
Primary
Base score
6.1
Impact score
2.7
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Severity
MEDIUM

Weaknesses

security-advisories@github.com
CWE-601

Social media

Hype score
Not currently trending

  1. 🔍 Lambda Watchdog detected that CVE-2025-50181 is no longer present in latest AWS Lambda base image scans. https://t.co/D1NCs5ZevN #AWS #Lambda #Security #CVE #DevOps #SecOps

    @LambdaWatchdog

    10 Jan 2026

    1 Impression

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  2. 🚨 Fedora 41 Security Alert! 🚨 CVE-2025-50181 affects python-pip. The bundled urllib3 didn't disable redirects when retries were off—a serious security misconfiguration. Read more: 👉 https://t.co/Z6Z7FXeZFe #Security https://t.co/hzy4d97yCs

    @Cezar_H_Linux

    28 Sept 2025

    50 Impressions

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    1 Like

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  3. Fedora 42: python-pip 2025-6d50efcd0c https://t.co/Hadwn7fdSY Security fix for the bundled urllib3 for CVE-2025-50181 #cybersecurity #cyber #security #hackers #cyberattack #databreach #incidentresponse #China

    @zeeshankghouri

    22 Sept 2025

    10 Impressions

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  4. 🚨 Urgent #Security Update for #SUSE & #openSUSE users! CVE-2025-50181 affects python-urllib3 (CVSS 6.0), risking data exposure. Affects: SLE 15 SP6/SP7, Leap 15.3, MicroOS 5.1-5.5. Read more: 👉 https://t.co/xTEf7dVWbb https://t.co/dUJrw31dBr

    @Cezar_H_Linux

    27 Aug 2025

    38 Impressions

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  5. URGENT: #Fedora41’s PyPy update fixes: CVE-2025-47273 (Path traversal) CVE-2024-47081 (.netrc leak) CVE-2025-50181 (urllib3 redirects) Update: sudo dnf upgrade --advisory FEDORA-2025-9b8da6ad7e Read more:👉 https://t.co/57SitW9GHj #DevSecOps https://t.co/65THK56L34

    @Cezar_H_Linux

    20 Jul 2025

    70 Impressions

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  6. 🔥 Breaking: #Ubuntu’s urllib3 has a CRITICAL flaw (CVE-2025-50181) leaking passwords/API keys! ✅ Patch: sudo apt update && sudo apt upgrade python3-urllib3 #LinuxSecurity #DevOps https://t.co/FKM83XISkf

    @Cezar_H_Linux

    26 Jun 2025

    28 Impressions

    0 Retweets

    2 Likes

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Configurations

Related CVEs

  1. urllib3 is an HTTP client library for Python. urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. urllib3 can perform decoding or decompression based on the HTTP `Content-Encoding` header (e.g., `gzip`, `deflate`, `br`, or `zstd`). When using the streaming API, the library decompresses only the necessary bytes, enabling partial content consumption. Starting in version 1.22 and prior to version 2.6.3, for HTTP redirect responses, the library would read the entire response body to drain the connection and decompress the content unnecessarily. This decompression occurred even before any read methods were called, and configured read limits did not restrict the amount of decompressed data. As a result, there was no safeguard against decompression bombs. A malicious server could exploit this to trigger excessive resource consumption on the client. Applications and libraries are affected when they stream content from untrusted sources by setting `preload_content=False` when they do not disable redirects. Users should upgrade to at least urllib3 v2.6.3, in which the library does not decode content of redirect responses when `preload_content=False`. If upgrading is not immediately possible, disable redirects by setting `redirect=False` for requests to untrusted source.•CVE-2026-21441
  2. urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.0 and prior to 2.6.0, the Streaming API improperly handles highly compressed data. urllib3's streaming API is designed for the efficient handling of large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once. When streaming a compressed response, urllib3 can perform decoding or decompression based on the HTTP Content-Encoding header (e.g., gzip, deflate, br, or zstd). The library must read compressed data from the network and decompress it until the requested chunk size is met. Any resulting decompressed data that exceeds the requested amount is held in an internal buffer for the next read operation. The decompression logic could cause urllib3 to fully decode a small amount of highly compressed data in a single operation. This can result in excessive resource consumption (high CPU usage and massive memory allocation for the decompressed data.•CVE-2025-66471
  3. 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.•CVE-2025-66418
  4. 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.•CVE-2025-50182
  5. urllib3 is a user-friendly HTTP client library for Python. When using urllib3's proxy support with `ProxyManager`, the `Proxy-Authorization` header is only sent to the configured proxy, as expected. However, when sending HTTP requests *without* using urllib3's proxy support, it's possible to accidentally configure the `Proxy-Authorization` header even though it won't have any effect as the request is not using a forwarding proxy or a tunneling proxy. In those cases, urllib3 doesn't treat the `Proxy-Authorization` HTTP header as one carrying authentication material and thus doesn't strip the header on cross-origin redirects. Because this is a highly unlikely scenario, we believe the severity of this vulnerability is low for almost all users. Out of an abundance of caution urllib3 will automatically strip the `Proxy-Authorization` header during cross-origin redirects to avoid the small chance that users are doing this on accident. Users should use urllib3's proxy support or disable automatic redirects to achieve safe processing of the `Proxy-Authorization` header, but we still decided to strip the header by default in order to further protect users who aren't using the correct approach. We believe the number of usages affected by this advisory is low. It requires all of the following to be true to be exploited: 1. Setting the `Proxy-Authorization` header without using urllib3's built-in proxy support. 2. Not disabling HTTP redirects. 3. Either not using an HTTPS origin server or for the proxy or target origin to redirect to a malicious origin. Users are advised to update to either version 1.26.19 or version 2.2.2. Users unable to upgrade may use the `Proxy-Authorization` header with urllib3's `ProxyManager`, disable HTTP redirects using `redirects=False` when sending requests, or not user the `Proxy-Authorization` header as mitigations.•CVE-2024-37891

References

Sources include official advisories and independent security research.