Check the server certificate when ssl_verify_identity is set by SashaMIT · Pull Request #1282 · PyMySQL/PyMySQL · GitHub

Summary

ssl_verify_identity=True with a CA and no ssl_verify_cert built a context with check_hostname and CERT_NONE. ssl rejects that pair, so Connection() raised ValueError: Cannot set verify_mode to CERT_NONE when check_hostname is enabled before any network I/O. Identity checks now use CERT_REQUIRED. A CA without identity checks is still CERT_NONE and does not check the hostname.

Fixes #1281

Test plan

Without the guard, pymysql/tests/test_ssl_verify_identity.py failed with that ValueError.
With the guard, python -m pytest -q pymysql/tests/test_ssl_verify_identity.py passed.
ruff format and ruff check passed on the changed files.

Summary by CodeRabbit

Bug Fixes
- TLS connections now require certificate verification whenever identity verification is enabled, regardless of the certificate-verification setting or whether a key password is provided. When identity verification is off, the certificate-verification setting determines whether certificates are checked. Verification remains disabled when neither option is enabled.

ssl_verify_identity=True with a CA and no ssl_verify_cert built a context with check_hostname and CERT_NONE. ssl rejects that pair, so Connection() raised ValueError before any network I/O.

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pymysql/connections.py

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📝 Walkthrough

Connection setup now selects certificate verification when ssl_verify_identity is enabled. Tests expect CERT_REQUIRED for identity verification, both with and without a key password.

Changes: TLS identity verification

Layer / File(s)	Summary
TLS verification mode and tests pymysql/connections.py, pymysql/tests/test_connection.py	Connection setup selects certificate verification when identity verification is enabled. Tests expect CERT_REQUIRED with and without a key password.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: methane

Merge Risk: ⚪ Minimal · up to a0f77

Identity verification now also enables certificate validation, resolving the reported SSL-context construction failure. No actionable merge-blocking risk is established.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly describes the main change: enabling server certificate checks when ssl_verify_identity is set. It is concise and specific.
Linked Issues check		The changes satisfy the coding requirements in [#1281]. When ssl_verify_identity is enabled, Connection.__init__ selects verification mode True. _create_ssl_ctx therefore uses `ssl.CERT_REQUIR…
Out of Scope Changes check		The changes remain within [#1281]. The production change selects certificate verification when identity checking is enabled. The test changes update the expected SSL context state for that behavior. N…

Full details: Linked Issues check

Explanation

The changes satisfy the coding requirements in [#1281]. When ssl_verify_identity is enabled, Connection.__init__ selects verification mode True. _create_ssl_ctx therefore uses ssl.CERT_REQUIRED, while hostname checking remains enabled. The tests update both identity-checking cases to expect ssl.CERT_REQUIRED. This removes the reported CERT_NONE and check_hostname=True conflict.

Full details: Out of Scope Changes check

Explanation

The changes remain within [#1281]. The production change selects certificate verification when identity checking is enabled. The test changes update the expected SSL context state for that behavior. No unrelated change is identified.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.19%. Comparing base (1e28be8) to head (a0f7724).
⚠️ Report is 82 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1282      +/-   ##
==========================================
- Coverage   86.24%   85.19%   -1.06%     
==========================================
  Files          17       17              
  Lines        2436     2492      +56     
  Branches      258      255       -3     
==========================================
+ Hits         2101     2123      +22     
- Misses        249      301      +52     
+ Partials       86       68      -18

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Actionable comments posted: 1

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Inline comments:
Review comments at @pymysql/connections.py:
- Around line 280-286: Update the SSL option handling in `Connection()` so
`ssl_verify_cert=False` combined with `ssl_verify_identity=True` and a CA does
not construct an invalid SSL context. Either reject the contradictory options
with a clear PyMySQL error or make identity verification select
`ssl.CERT_REQUIRED`.

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Reviewing files that changed from the base of the PR and between 31126a3 and b9dbae7.

📒 Files selected for processing (3)

pymysql/connections.py
pymysql/tests/test_connection.py
pymysql/tests/test_ssl_verify_identity.py

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Thanks for the merge.

Check the server certificate when ssl_verify_identity is set.

b9dbae7

ssl_verify_identity=True with a CA and no ssl_verify_cert built a context with check_hostname and CERT_NONE. ssl rejects that pair, so Connection() raised ValueError before any network I/O.

coderabbitai Bot reviewed Oct 9, 2026

View reviewed changes

Comment thread pymysql/connections.py Outdated

simplify

a0f7724

methane force-pushed the fix/ssl-verify-identity branch from ff5ecfd to a0f7724 Compare October 18, 2026 14:23

methane merged commit 4399e30 into PyMySQL:main Oct 18, 2026
14 checks passed

Check the server certificate when ssl_verify_identity is set by SashaMIT · Pull Request #1282 · PyMySQL/PyMySQL · GitHub

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Check the server certificate when ssl_verify_identity is set - #1282

Check the server certificate when ssl_verify_identity is set#1282
methane merged 2 commits into
PyMySQL:mainfrom
SashaMIT:fix/ssl-verify-identity

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Check the server certificate when ssl_verify_identity is set by SashaMIT · Pull Request #1282 · PyMySQL/PyMySQL · GitHub

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Check the server certificate when ssl_verify_identity is set - #1282

Check the server certificate when ssl_verify_identity is set#1282methane merged 2 commits intoPyMySQL:mainPyMySQL/PyMySQL:mainfrom SashaMIT:fix/ssl-verify-identitySashaMIT/PyMySQL:fix/ssl-verify-identityCopy head branch name to clipboard

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Check the server certificate when ssl_verify_identity is set#1282
methane merged 2 commits into
PyMySQL:mainfrom
SashaMIT:fix/ssl-verify-identity

SashaMIT commented Oct 9, 2026 •
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