CVE-2026-53727

NameCVE-2026-53727
Descriptioncss_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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
ruby-css-parser (PTS)bullseye1.6.0-1vulnerable
bookworm1.6.0-2+deb12u1vulnerable
trixie1.19.0-1+deb13u1vulnerable
forky, sid3.0.0-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
ruby-css-parsersource(unstable)3.0.0-1

Notes

https://github.com/premailer/css_parser/security/advisories/GHSA-9pmc-p236-855h
Fixed by: https://github.com/premailer/css_parser/commit/7d2ddf0189cd54b54f378f59daefa10cb036e476 (v3.0.0)
Fixed by: https://github.com/premailer/css_parser/commit/e0a151458b2a801ae265ba420862ef8b1127b3ae (v3.0.0)

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