CSS Parser: Improper Certificate Validation allows MITM injection of remote CSS content

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0015, the 3rd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the GitHub Advisory Database, published 7 May 2026. New records show when each source confirmed them.

Sources

• GitHub Advisory Database: GHSA-ff6c-w6qf-7xqc
• OSV: GHSA-ff6c-w6qf-7xqc
• github.com/premailer/css_parser/security/advisories/GHSA-ff6c-w6qf-7xqc
• nvd.nist.gov/vuln/detail/CVE-2026-44312
• github.com/premailer/css_parser/issues/185
• github.com/premailer/css_parser/commit/35e689c904225add78e0c488cf04bad052666449
• github.com/premailer/css_parser/commit/e0c95d5abe91b237becb90ff316531a6547ada18
• github.com/premailer/css_parser
• github.com/rubysec/ruby-advisory-db/blob/master/gems/css_parser/CVE-2026-44312.yml

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.