CSS Parser: Improper Certificate Validation allows MITM injection of remote CSS content — CVE-2026-44312

Summary

### Summary The CSS Parser gem does not validate HTTPS connections, allowing a Man-in-the-Middle (MITM) attacker to inject or modify CSS content when stylesheets are loaded via HTTPS. The connection is established with `OpenSSL::SSL::VERIFY_NONE`, meaning any HTTPS certificate—even entirely untrusted—will be accepted without validation. ### Details In `lib/css_parser/parser.rb`, the HTTP client sets:…

Product

rubygems: css_parser

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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