CVE-2026-44312

Description

css_parser is a Ruby CSS parser. Prior to 2.1.0 and 1.22.0, 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. This vulnerability is fixed in 2.1.0 and 1.22.0.

References

• https://github.com/premailer/css_parser/commit/35e689c904225add78e0c488cf04bad052666449
• https://github.com/premailer/css_parser/commit/e0c95d5abe91b237becb90ff316531a6547ada18
• https://github.com/premailer/css_parser/issues/185
• https://github.com/premailer/css_parser/security/advisories/GHSA-ff6c-w6qf-7xqc