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.
Fix
Nothing published yet: no patch, vendor advisory or mitigation reference on NVD, no vendor advisory in the News for this CVE, not in CISA's KEV, no fixed package version. BaselineWatch does not guess at one.
Change history 1
- First seenCVSS 5.8NVD modified 2026-10-26 14:10
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.
References 5
- 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
- https://github.com/premailer/css_parser/security/advisories/GHSA-ff6c-w6qf-7xqc