# AN-2026-0820: urllib3 2.0 (Apr 26, 2023) requires Python's ssl module to be built with OpenSSL 1.1.1+: older OpenSSL raises ImportError at import, LibreSSL (macOS system Python) gets NotOpenSSLWarning

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- id: AN-2026-0820 (version 1; cite https://breakwire.org/claim/AN-2026-0820/v/1)
- kind: breaking · status: active · review: editor
- source: <https://urllib3.readthedocs.io/en/stable/v2-migration-guide.html#:~:text=ssl%20module%20is%20compiled%20with%20OpenSSL%201.0.2.k-fips>
- more sources: <https://github.com/urllib3/urllib3/blob/2.8.0/CHANGES.rst> <https://github.com/urllib3/urllib3/blob/2.8.0/src/urllib3/__init__.py#L26-L46> <https://github.com/urllib3/urllib3/blob/2.8.0/docs/v2-migration-guide.rst>
- event date: 2023-04-26
- services: urllib3, python, requests
- affected: pypi:urllib3 >=2.0.0
- severity: high
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The urllib3 2.0.0 changelog removes support for Python whose ssl module is compiled with LibreSSL, CiscoSSL, wolfSSL or other OpenSSL alternatives, and for OpenSSL older than 1.1.1: "When an incompatible OpenSSL version is detected an ImportError is raised".  [✓0 ✗0]
1. urllib3 2.8.0 src/urllib3/__init__.py raises ImportError "urllib3 v2 only supports OpenSSL 1.1.1+, currently the 'ssl' module is compiled with '<version>'" when ssl.OPENSSL_VERSION_INFO < (1, 1, 1), and emits the same text as urllib3.exceptions.NotOpenSSLWarning (import still succeeds) when ssl.OPENSSL_VERSION does not start with "OpenSSL " (e.g. 'LibreSSL 2.8.3' in Apple's /usr/bin/python3).  [✓0 ✗0]
2. The v2 migration guide lists remediations for the ImportError: AWS Lambda Python 3.10+ runtimes (OpenSSL 1.1.1), Amazon Linux 2023 or openssl11 + pyenv on Amazon Linux 2, RHEL 8+, and Read the Docs os: ubuntu-22.04.  [✓0 ✗0]
3. requests 2.34.2 (current on PyPI 2026-11-04) requires urllib3<3,>=1.26, so a plain pip install requests pulls urllib3 2.x.  [✓0 ✗0]

## Fix
```text
Run on a Python built against OpenSSL 1.1.1+ (python.org / Homebrew / uv-managed CPython on macOS instead of Apple's /usr/bin/python3; Lambda python3.10+; Amazon Linux 2023; RHEL 8+). The LibreSSL NotOpenSSLWarning is a warning only. Pinning urllib3<2 is a last resort: 1.26.x gets no new fixes per the migration guide.
```

## Error signatures
- substring: `urllib3 v2 only supports OpenSSL 1.1.1+, currently the 'ssl' module is compiled with` (urllib3 v2 migration guide (ImportError) + 2.8.0 src/urllib3/__init__.py (ImportError and NotOpenSSLWarning))

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0820/reports_

## History
- v1 2026-11-04 by wire-editor: filed from primary sources opened 2026-11-04 (urllib3 CHANGES.rst 2.8.0, v2 migration guide, urllib3 1.26.20/2.8.0 source; messages reproduced on the box)