Requests Requests tries to resolve `user:pass@host` on OS X

The Fix

pip install requests==2.27.0

Based on closed psf/requests issue #4275 · PR/commit linked

Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.

Jump to Verify Open PR/Commit

@@ -182,3 +182,4 @@ Patches and Suggestions
 - Nehal J Wani (`@nehaljwani <https://github.com/nehaljwani>`_)
 - Demetrios Bairaktaris (`@DemetriosBairaktaris <https://github.com/demetriosbairaktaris>`_)
+- Darren Dormer (`@ddormer <https://github.com/ddormer>`_)
diff --git a/HISTORY.rst b/HISTORY.rst
index b099ecdb1b..db1d1f7043 100644

repro.py

{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "2.6"
  },
  "implementation": {
    "name": "CPython",
    "version": "2.7.10"
  },
  "platform": {
    "release": "15.6.0",
    "system": "Darwin"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.18.4"
  },
  "system_ssl": {
    "version": "100020cf"
  },
  "urllib3": {
    "version": "1.22"
  },
  "using_pyopenssl": false
}

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

fix.md

Option A — Upgrade to fixed release\npip install requests==2.27.0\nWhen NOT to use: This fix is not applicable if the application requires credentials in the URL.\n\n

Why This Fix Works in Production

Trigger: "pyOpenSSL": {
Mechanism: Proxy bypass logic is called before stripping credentials from the URL
Why the fix works: Fixes an issue where DNS resolution included authentication credentials in proxy bypass settings on macOS. (first fixed release: 2.27.0).

Production impact:

If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.

Why This Breaks in Prod

Proxy bypass logic is called before stripping credentials from the URL
Production symptom (often without a traceback): "pyOpenSSL": {

Proof / Evidence

GitHub issue: #4275
Fix PR: https://github.com/psf/requests/pull/4427
First fixed release: 2.27.0
Reproduced locally: No (not executed)
Last verified: 2026-02-07
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.57

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“So this seems to be an issue with macOS specifically, and in particular how it handles proxy bypass. We should probably strip the auth from…”

@Lukasa · 2017-09-05 · source

Failure Signature (Search String)

"pyOpenSSL": {
"openssl_version": "",

Copy-friendly signature

signature.txt

Failure Signature
-----------------
"pyOpenSSL": {
"openssl_version": "",

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
"pyOpenSSL": {
"openssl_version": "",

Minimal Reproduction

repro.py

{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "2.6"
  },
  "implementation": {
    "name": "CPython",
    "version": "2.7.10"
  },
  "platform": {
    "release": "15.6.0",
    "system": "Darwin"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.18.4"
  },
  "system_ssl": {
    "version": "100020cf"
  },
  "urllib3": {
    "version": "1.22"
  },
  "using_pyopenssl": false
}

What Broke

DNS resolution attempts are made for invalid hostnames with credentials.

Why It Broke

Proxy bypass logic is called before stripping credentials from the URL

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

pip install requests==2.27.0

When NOT to use: This fix is not applicable if the application requires credentials in the URL.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Fix reference: https://github.com/psf/requests/pull/4427

First fixed release: 2.27.0

Last verified: 2026-02-07. Validate in your environment.

When NOT to Use This Fix

This fix is not applicable if the application requires credentials in the URL.

Verify Fix

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Add a TLS smoke test that performs a real handshake in CI (include CA bundle validation and hostname checks).
Alert on handshake failures by error string and endpoint to catch cert/CA changes quickly.

Version Compatibility Table

Version	Status
2.27.0	Fixed

Related Issues

No related fixes found.

Cluster: requests:configuration-error Requests hub Requests best practices All hubs All clusters

Related clusters: Data consistency SSL handshake Other

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.

Requests Requests tries to resolve `user:pass@host` on OS X (Fix)