# urllib3 (PyPI) vulnerabilities

Source: https://junglewise.ai/threats/technologies/urllib3  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Updated: 13 November 2026, 03:07 UTC. Rebuilt every hour.  
Data: https://junglewise.ai/threats/technologies/urllib3.json  
License: CC BY 4.0 with a link back

Junglewise Threat Intelligence has tracked 25 vulnerabilities in urllib3 (PyPI): 0 in the last 7 days and 3 in the last 90 days, 0 of them critical and 0 exploited in the wild. The most recent, CVE-2026-97689, was published on 29 September 2026. Nothing in the last four weeks, down from 3 vulnerabilities in the four before.

## Counts

- Last 7 days: 0
- Last 30 days: 0
- Last 90 days: 3
- All time: 25 (0 critical, 0 exploited in the wild)

## About urllib3 (PyPI)

Python HTTP client library for making requests and handling connections.

## Latest urllib3 (PyPI) vulnerabilities

- [CVE-2026-97689: urllib3 HTTP client unbounded memory allocation in chunked transfer](https://junglewise.ai/threats/cve-2026-97689-urllib3-is-an-http-client-library-for-python-from-1-10-3-until-2) (high, CVSS 4, published 29 Sep 2026)
- [CVE-2026-97688: urllib3 infinite loop in Deflate decoder](https://junglewise.ai/threats/cve-2026-97688-urllib3-is-an-http-client-library-for-python-from-2-6-2-until-2-8) (medium, CVSS 4, published 29 Sep 2026)
- [CVE-2026-97687: urllib3 HTTPS proxy TLS settings isolation](https://junglewise.ai/threats/cve-2026-97687-urllib3-is-an-http-client-library-for-python-from-1-26-0-until-2) (high, CVSS 4, published 29 Sep 2026)
- [CVE-2025-50182: PYSEC-2026-1997 - urllib3 does not control redirects in browsers and Node.js](https://junglewise.ai/threats/cve-2025-50182-urllib3-does-not-control-redirects-in-browsers-and-node-js) (low, CVSS 3.1, published 7 Jul 2026)
- [CVE-2025-50181: PYSEC-2026-1999 - urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation](https://junglewise.ai/threats/cve-2025-50181-urllib3-redirects-are-not-disabled-when-retries-are-disabled-on) (low, CVSS 3.1, published 7 Jul 2026)
- [CVE-2024-37891: PYSEC-2026-1995 - urllib3's Proxy-Authorization request header isn't stripped during cross-origin redirects](https://junglewise.ai/threats/cve-2024-37891-urllib3-proxy-authorization-header-leak-in-cross-origin-redirects) (low, CVSS 3.1, published 7 Jul 2026)
- [CVE-2026-9375: urllib3 denial of service via Brotli decompression bomb bypass](https://junglewise.ai/threats/cve-2026-9375-urllib3-denial-of-service-via-brotli-decompression-bomb-bypass) (high, CVSS 7.5, published 19 Jun 2026)
- [CVE-2026-44432: urllib3 resource exhaustion via improper handling of compressed data](https://junglewise.ai/threats/cve-2026-44432-urllib3-resource-exhaustion-via-improper-handling-of-compressed) (high, CVSS 7.5, published 13 May 2026)
- [CVE-2026-44431: urllib3 sensitive header leak in ProxyManager low-level redirects](https://junglewise.ai/threats/cve-2026-44431-urllib3-sensitive-header-leak-in-proxymanager-low-level-redirects) (medium, CVSS 5.3, published 13 May 2026)
- [CVE-2026-21441: Python urllib3 denial of service via decompression bomb in redirects](https://junglewise.ai/threats/cve-2026-21441-python-urllib3-denial-of-service-via-decompression-bomb-in) (high, CVSS 7.5, published 7 Jan 2026)
- [CVE-2025-66471: urllib3 streaming API improper compression handling](https://junglewise.ai/threats/cve-2025-66471-urllib3-streaming-api-improper-compression-handling) (high, CVSS 7.5, published 5 Dec 2025)
- [CVE-2025-66418: PYSEC-2026-1998 - urllib3 allows an unbounded number of links in the decompression chain](https://junglewise.ai/threats/cve-2025-66418-urllib3-is-a-user-friendly-http-client-library-for-python) (high, CVSS 7.5, published 5 Dec 2025)
- [CVE-2023-45803: urllib3's request body not stripped after redirect from 303 status changes request method to GET](https://junglewise.ai/threats/cve-2023-45803-urllib3-s-request-body-not-stripped-after-redirect-from-303) (low, CVSS 3.1, published 17 Oct 2023)
- [CVE-2018-25091: Authorization Header forwarded on redirect](https://junglewise.ai/threats/cve-2018-25091-authorization-header-forwarded-on-redirect) (low, CVSS 3.1, published 15 Oct 2023)
- [CVE-2023-43804: `Cookie` HTTP header isn't stripped on cross-origin redirects](https://junglewise.ai/threats/cve-2023-43804-cookie-http-header-isn-t-stripped-on-cross-origin-redirects) (low, CVSS 3.1, published 4 Oct 2023)
- [CVE-2021-33503: urllib3 ReDoS in URL authority parser](https://junglewise.ai/threats/cve-2021-33503-urllib3-redos-in-url-authority-parser) (high, CVSS 7.5, published 1 Jun 2021)
- [CVE-2021-28363: Using default SSLContext for HTTPS requests in an HTTPS proxy doesn't verify certificate hostname for proxy connection](https://junglewise.ai/threats/cve-2021-28363-using-default-sslcontext-for-https-requests-in-an-https-proxy) (low, CVSS 3.1, published 15 Mar 2021)
- [CVE-2020-26137: CRLF injection in urllib3](https://junglewise.ai/threats/cve-2020-26137-crlf-injection-in-urllib3) (low, CVSS 3.1, published 30 Sep 2020)
- [CVE-2020-7212: Uncontrolled Resource Consumption in urllib3](https://junglewise.ai/threats/cve-2020-7212-uncontrolled-resource-consumption-in-urllib3) (low, CVSS 3.1, published 6 Mar 2020)
- [CVE-2019-11324: Improper Certificate Validation in urllib3](https://junglewise.ai/threats/cve-2019-11324-improper-certificate-validation-in-urllib3) (low, CVSS 3, published 18 Apr 2019)
- [PYSEC-2019-63 - The urllib3 library before 1.24.2 for Python mishandles certain cases where the desired set of CA…](https://junglewise.ai/threats/pysec-2019-63-the-urllib3-library-before-1-24-2-for-python-mishandles-2035a86a) (info, published 18 Apr 2019)
- [PYSEC-2019-62 - In the urllib3 library through 1.24.1 for Python, CRLF injection is possible if the attacker controls the request parameter.](https://junglewise.ai/threats/pysec-2019-62-in-the-urllib3-library-through-1-24-1-for-python-crlf-2b64885a) (info, published 15 Apr 2019)
- [CVE-2019-11236: PYSEC-2019-132 - In the urllib3 library through 1.24.1 for Python, CRLF injection is possible if the attacker controls the…](https://junglewise.ai/threats/cve-2019-11236-improper-neutralization-of-crlf-sequences-in-urllib3-library-for) (low, CVSS 3, published 15 Apr 2019)
- [CVE-2018-20060: Exposure of Sensitive Information to an Unauthorized Actor in urllib3](https://junglewise.ai/threats/cve-2018-20060-exposure-of-sensitive-information-to-an-unauthorized-actor-in) (low, CVSS 3, published 11 Dec 2018)
- [CVE-2016-9015: Urllib3 Incorrect Certificate Validation](https://junglewise.ai/threats/cve-2016-9015-urllib3-incorrect-certificate-validation) (low, CVSS 3, published 11 Jan 2017)

## Most severe urllib3 (PyPI) vulnerabilities

- [CVE-2021-33503: urllib3 ReDoS in URL authority parser](https://junglewise.ai/threats/cve-2021-33503-urllib3-redos-in-url-authority-parser) (high, CVSS 7.5, published 1 Jun 2021)
- [CVE-2026-21441: Python urllib3 denial of service via decompression bomb in redirects](https://junglewise.ai/threats/cve-2026-21441-python-urllib3-denial-of-service-via-decompression-bomb-in) (high, CVSS 7.5, published 7 Jan 2026)
- [CVE-2026-44432: urllib3 resource exhaustion via improper handling of compressed data](https://junglewise.ai/threats/cve-2026-44432-urllib3-resource-exhaustion-via-improper-handling-of-compressed) (high, CVSS 7.5, published 13 May 2026)
- [CVE-2025-66471: urllib3 streaming API improper compression handling](https://junglewise.ai/threats/cve-2025-66471-urllib3-streaming-api-improper-compression-handling) (high, CVSS 7.5, published 5 Dec 2025)
- [CVE-2025-66418: PYSEC-2026-1998 - urllib3 allows an unbounded number of links in the decompression chain](https://junglewise.ai/threats/cve-2025-66418-urllib3-is-a-user-friendly-http-client-library-for-python) (high, CVSS 7.5, published 5 Dec 2025)
- [CVE-2026-9375: urllib3 denial of service via Brotli decompression bomb bypass](https://junglewise.ai/threats/cve-2026-9375-urllib3-denial-of-service-via-brotli-decompression-bomb-bypass) (high, CVSS 7.5, published 19 Jun 2026)
- [CVE-2026-97689: urllib3 HTTP client unbounded memory allocation in chunked transfer](https://junglewise.ai/threats/cve-2026-97689-urllib3-is-an-http-client-library-for-python-from-1-10-3-until-2) (high, CVSS 4, published 29 Sep 2026)
- [CVE-2026-97687: urllib3 HTTPS proxy TLS settings isolation](https://junglewise.ai/threats/cve-2026-97687-urllib3-is-an-http-client-library-for-python-from-1-26-0-until-2) (high, CVSS 4, published 29 Sep 2026)
- [CVE-2026-44431: urllib3 sensitive header leak in ProxyManager low-level redirects](https://junglewise.ai/threats/cve-2026-44431-urllib3-sensitive-header-leak-in-proxymanager-low-level-redirects) (medium, CVSS 5.3, published 13 May 2026)
- [CVE-2026-97688: urllib3 infinite loop in Deflate decoder](https://junglewise.ai/threats/cve-2026-97688-urllib3-is-an-http-client-library-for-python-from-2-6-2-until-2-8) (medium, CVSS 4, published 29 Sep 2026)

## Vulnerabilities per week

Nothing in the last four weeks, down from 3 vulnerabilities in the four before.

| Week of | Vulns | Critical | Exploited |
| --- | --- | --- | --- |
| 17 Aug 2026 | 0 | 0 | 0 |
| 24 Aug 2026 | 0 | 0 | 0 |
| 31 Aug 2026 | 0 | 0 | 0 |
| 7 Sep 2026 | 0 | 0 | 0 |
| 14 Sep 2026 | 0 | 0 | 0 |
| 21 Sep 2026 | 0 | 0 | 0 |
| 28 Sep 2026 | 3 | 0 | 0 |
| 5 Oct 2026 | 0 | 0 | 0 |
| 12 Oct 2026 | 0 | 0 | 0 |
| 19 Oct 2026 | 0 | 0 | 0 |
| 26 Oct 2026 | 0 | 0 | 0 |
| 2 Nov 2026 | 0 | 0 | 0 |
| 9 Nov 2026 | 0 | 0 | 0 |

## Other PyPI technologies

- [tensorflow (PyPI)](https://junglewise.ai/threats/technologies/pypi-tensorflow): 435 vulnerabilities
- [tensorflow-cpu (PyPI)](https://junglewise.ai/threats/technologies/tensorflow-cpu): 430 vulnerabilities
- [tensorflow-gpu (PyPI)](https://junglewise.ai/threats/technologies/tensorflow-gpu): 427 vulnerabilities
- [open-webui (PyPI)](https://junglewise.ai/threats/technologies/open-webui): 177 vulnerabilities
- [Django (PyPI)](https://junglewise.ai/threats/technologies/django): 173 vulnerabilities
- [apache-airflow (PyPI)](https://junglewise.ai/threats/technologies/apache-airflow): 159 vulnerabilities
- [pillow (PyPI)](https://junglewise.ai/threats/technologies/pillow): 125 vulnerabilities
- [praisonai (PyPI)](https://junglewise.ai/threats/technologies/pypi-praisonai): 120 vulnerabilities
- [vllm (PyPI)](https://junglewise.ai/threats/technologies/pypi-vllm): 117 vulnerabilities
- [plone (PyPI)](https://junglewise.ai/threats/technologies/pypi-plone): 101 vulnerabilities
- [mlflow (PyPI)](https://junglewise.ai/threats/technologies/mlflow): 88 vulnerabilities
- [picklescan (PyPI)](https://junglewise.ai/threats/technologies/picklescan): 86 vulnerabilities

## Sources

NVD, GitHub Security Advisories, OSV, the CISA Known Exploited Vulnerabilities catalog, FIRST EPSS and vendor advisories. Rebuilt every hour. Cite as: Junglewise Threat Intelligence, "urllib3 (PyPI) vulnerabilities", https://junglewise.ai/threats/technologies/urllib3, 13 November 2026.