CVE-2018-20060

CVE-2018-20060 affects urllib3/python-urllib3 prior to 1.23, where the Authorization header is not removed on cross-origin redirects. This can allow credentials in the Authorization header to be exposed to unintended hosts or transmitted in cleartext. Public sources in the Connected documents ind...

CVE-2021-33503

CVE-2021-33503 affects urllib3 prior to 1.26.5, where the authority component regex can catastrophically backtrack on URLs containing many @ characters, leading to denial of service via parameters or redirects. Several connected sources note a patched version is available (e.g., python-urllib3 up...

CVE-2020-26137

CVE-2020-26137 pertains to Python’s urllib3 and is explicitly described as a CRLF injection vulnerability in the HTTP request handling of urllib3/http.client. The connected advisories show affected package and version details: python-urllib3 1.24.2-2 (CBLMariner entry) and a recommended upgrade t...

CVE-2023-43804

CVE-2023-43804 affects the Python urllib3 library, where a Cookie header may be leaked across cross-origin redirects if redirects are not disabled. The issue is resolved in urllib3 1.26.17 or 2.0.5. Affected environments are confirmed in multiple reports, including AlmaLinux and Brocade advisorie...

CVE-2019-11236

The CVE-2019-11236 entry affects Python’s urllib3 up to version 1.24.1, where an attacker controlling a request parameter can trigger CRLF injection. Multiple connected advisories corroborate this issue and cite potential header/credential exposure risks in cross-origin redirects or crafted reque...

CVE-2019-11324

The issue CVE-2019-11324 affects the Python urllib3 library prior to 1.24.2, where SSL verification can be bypassed when the SSLContext, ca_certs, or ca_certs_dir arguments differ from the OS CA store, causing TLS handshakes to succeed when they should fail. This is related to how system vs manua...

CVE-2023-45803

CVE-2023-45803 affects the Python urllib3 library. The issue arises when handling HTTP redirects (301/302/303) after a request’s method changes from something that can carry a body (e.g., POST) to GET, where urllib3 previously did not remove the HTTP request body. This could allow leakage of sens...

CVE-2024-37891

CVE-2024-37891 affects urllib3 (Python HTTP client) across multiple distributions (e.g., python3-urllib3, python3.13-pip, python-pip, etc.). The issue: when not using urllib3’s ProxyManager proxy support, a configured Proxy-Authorization header could be sent, and urllib3 may not strip it on cross...

CVE-2025-50181

CVE-2025-50181 affects python-urllib3 and was fixed in urllib3 2.5.0. Several connected advisories confirm vulnerable versions are older releases (e.g., python-urllib3

CVE-2018-25091

CVE-2018-25091 affects the urllib3 library (before 1.24.2). When following cross-origin redirects, urllib3 may not remove the Authorization header, allowing credentials to be exposed to unintended hosts or transmitted in cleartext. This is noted as a follow-on from an incomplete fix for CVE-2018-...

CVE-2026-44432

CVE-2026-44432 affects urllib3 before 2.7.0, where the library could decompress the entire response during HTTPResponse.read or drain_conn, leading to high CPU and memory usage when handling highly compressed data. Affected versions: 2.6.0 up to (but not including) 2.7.0. Impact described as pote...

CVE-2021-28363

CVE-2021-28363 affects urllib3 for Python: versions 1.26.x before 1.26.4 omit SSL certificate validation when connecting HTTPS to HTTPS proxies, potentially enabling MITM via proxy hostname mismatch. Impact is partial confidentiality. Remediation: upgrade urllib3 to 1.26.4 or later (patched versi...

CVE-2026-21441

CVE-2026-21441 (urllib3) : The issue occurs in urllib3’s streaming API where, for HTTP redirect responses, the client decompresses the entire response body even before any reads are issued, enabling potential resource exhaustion (CPU/memory) via decompression bombs. Affected versions are prior to...

CVE-2026-44431

CVE-2026-44431 affects urllib3 (Python HTTP client). From versions 1.23 up to, but not including, 2.7.0, cross-origin redirects followed by the low‑level API via ProxyManager.connection_from_url().urlopen(..., assert_same_host=False) still forward sensitive headers. This constitutes a leakage of ...

CVE-2025-50182

CVE-2025-50182 : Affects urllib3 (Python HTTP client). The issue is that prior to 2.5.0, when urllib3 is used in environments like Pyodide (Python in a browser/Node via Fetch/XMLHttpRequest), redirects are not controlled; Pyodide determines redirect behavior, and retries/redirect params are ignor...

CVE-2020-7212

CVE-2020-7212 concerns urllib3 for Python (versions 1.25.2–1.25.7) with a Denial of Service risk caused by the _encode_invalid_chars implementation in util/url.py. The issue arises from an inefficient algorithm where the percent_encodings collection can grow O(N) for a URL of length N, and the su...

CVE-2016-9015

CVE-2016-9015 affects Python urllib3 versions 1.17 and 1.18 when using PyOpenSSL with OpenSSL 1.1.0; in such configurations TLS certificate validation can be bypassed, enabling MITM and information leakage. The issue is considered low impact due to the very specific configuration. remediation fro...

CVE-2025-66418

The connected advisories confirm CVE-2025-66418 affects urllib3 (Python) via an unbounded decompression chain in versions 1.24 up to before 2.6.0, enabling high CPU and memory usage; remediation is to upgrade to 2.6.0 or later. Additional advisories note related issues: CVE-2025-66471 (Streaming ...

CVE-2025-66471

CVE-2025-66471 affects urllib3’s streaming API handling of compressed HTTP responses in Python. The issue arises when streaming a highly compressed payload, where decompression could process data in a way that uses excessive CPU and memory, potentially from the decompression buffer behavior noted...

CVE-2026-97687

The urllib3 Python HTTP client library (versions 1.26.0 through 2.8.0 ) contains a vulnerability where target-server TLS settings are incorrectly applied to HTTPS proxy connections. Specifically, configurations like proxy_ssl_context, ssl_context, and cert_reqs fail to remain separated, allowing ...

CVE-2026-97689

The urllib3 Python HTTP client library (versions 1.10.3 through 2.8.0 ) is vulnerable to an unbounded memory allocation issue in the HTTPResponse.read_chunked and HTTPResponse.stream methods. The root cause is that the streaming chunk parser buffers the chunk-size field until it encounters a newl...

CVE-2026-97688

The Python HTTP client library urllib3 versions 2.6.2 through 2.8.0 are vulnerable to an infinite loop during chunked Deflate streaming. The issue exists because the Deflate decoder retains trailing bytes as unconsumed input after reaching the end-of-stream, repeatedly decoding them without progr...