Server-Side Request Forgery (SSRF) Affecting ruby-css-parser package, versions <3.0.0-1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.51% (41st percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-RUBYCSSPARSER-18015605
  • published19 Jul 2026
  • disclosed17 Jul 2026

Introduced: 17 Jul 2026

CVE-2026-53727  (opens in a new tab)
CWE-918  (opens in a new tab)

How to fix?

Upgrade Debian:unstable ruby-css-parser to version 3.0.0-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream ruby-css-parser package and not the ruby-css-parser package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1