{"id":"CVE-2026-53727","aliases":["GHSA-9pmc-p236-855h"],"url":"https://o3.security/vulnerability/CVE-2026-53727","summary":"css_parser: SSRF and Local File Disclosure in `CssParser::Parser#read_remote_file`","details":"css_parser is a Ruby CSS parser. From 2.2.0 until 3.0.0, CssParser::Parser#read_remote_file in lib/css_parser/parser.rb, and therefore load_uri! and the @import-following branch of add_block!, issued HTTP and HTTPS requests against any host, port, and URI without a scheme allowlist, host or IP filtering, or protection against link-local, loopback, or RFC-1918 addresses. Location: redirects were followed recursively back into the same function, which also serviced file:// URIs, so a single attacker-controlled HTTP redirect could upgrade the bug from SSRF to arbitrary local file disclosure. Any consumer of css_parser that hands it attacker-influenced CSS together with a base_uri: option is exposed. This issue is fixed in version 3.0.0.","published":"2026-07-17T20:30:37.291Z","modified":"2026-08-20T03:54:27.165515396Z","cvss":null,"epss":{"score":0.00365,"percentile":0.29412,"asOf":"2026-08-31"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"RubyGems","name":"css_parser","fixedVersion":"3.0.0"}],"fix":{"url":"https://github.com/premailer/css_parser/commit/7d2ddf0189cd54b54f378f59daefa10cb036e476","label":"premailer/css_parser@7d2ddf0"},"references":[{"type":"WEB","url":"https://github.com/premailer/css_parser/releases/tag/v3.0.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53727.json"},{"type":"ADVISORY","url":"https://github.com/premailer/css_parser/security/advisories/GHSA-9pmc-p236-855h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53727"},{"type":"FIX","url":"https://github.com/premailer/css_parser/commit/7d2ddf0189cd54b54f378f59daefa10cb036e476"},{"type":"FIX","url":"https://github.com/premailer/css_parser/commit/e0a151458b2a801ae265ba420862ef8b1127b3ae"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-20T03:54:27.165515396Z"}}