Ruby CSS Parser: SSRF and Local File Disclosure in `CssParser::Parser#read_remote_file`

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 0.0051, the 43rd 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 9 Jul 2026. New records show when each source confirmed them.

Sources

• GitHub Advisory Database: GHSA-9pmc-p236-855h
• OSV: GHSA-9pmc-p236-855h
• github.com/premailer/css_parser/security/advisories/GHSA-9pmc-p236-855h
• github.com/premailer/css_parser
• github.com/rubysec/ruby-advisory-db/blob/master/gems/css_parser/CVE-2026-53727.yml
• www.cve.org/CVERecord/SearchResults?query=CVE-2026-53727

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.