Python adds a blocklist of compromised intermediate certificates to the ssl module

What happened and what to do

The advisory, published by the Python security team and relayed on the oss-security list on 24 October 2026, states that the ssl module now includes a blocklist of intermediate certificates known to be compromised. The stated goal is to protect users.

For companies running Python in servers, data pipelines or agents, the practical question is which environments use affected versions and when they will receive the fix. A consultancy engagement can map runtimes and dependencies, build an inventory of Python versions per service, prioritise the upgrade and set up monitoring that alerts on new security advisories. It is also possible to test in staging how the TLS connections of internal systems behave before the change reaches production.

How the consultancy can help

Diagnosis of exposure to Python versions and TLS libraries, with a per-service inventory, a prioritised upgrade plan and connection tests in staging. Implementation of continuous monitoring for security advisories and operation of the remediation process.

Next step

If your company runs Python in production and wants to understand how this advisory affects your systems, send a short description of your environment. You will receive a proposal with a defined scope for the diagnosis and remediation.