CVE-2026-53727
Premailer Css Parser server-side request forgery (SSRF)
- Published17 Jul 2026
Description
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 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:NAffected products
Remediation
No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.
References
- https://github.com/premailer/css_parser/commit/7d2ddf0189cd54b54f378f59daefa10cb036e476
- https://github.com/premailer/css_parser/commit/e0a151458b2a801ae265ba420862ef8b1127b3ae
- https://github.com/premailer/css_parser/releases/tag/v3.0.0
- https://github.com/premailer/css_parser/security/advisories/GHSA-9pmc-p236-855h
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-53727 being actively exploited?
CVE-2026-53727 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.51%.
How severe is CVE-2026-53727?
CVE-2026-53727 has a CVSS 3.1 base score of 8.6, rated high. EPSS estimates a 0.51% probability of exploitation.
Which products are affected by CVE-2026-53727?
Affected products include Premailer Css Parser.
How do I fix CVE-2026-53727?
Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-53727 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.