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CVE-2026-53727

8.6 · HIGH

css_parser is a Ruby CSS parser.

Published Jul 17, 2026CWE-918EPSS 0.51%

Overview

CVE-2026-53727 is a high-severity vulnerability. It was published on July 17, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/premailer/css_parser/commit/7d2ddf0189cd54b54f378f59daefa10cb036e476GitHubgithub.com/premailer/css_parser/commit/e0a151458b2a801ae265ba420862ef8b1127b3aeGitHubgithub.com/premailer/css_parser/releases/tag/v3.0.0GitHubgithub.com/premailer/css_parser/security/advisories/GHSA-9pmc-p236-855hGitHubgithub.com/premailer/css_parser/security/advisories/GHSA-9pmc-p236-855h

How CyberStrike helps

Frequently asked questions

What is CVE-2026-53727?

CVE-2026-53727 is a high-severity vulnerability. It was published on July 17, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).

How severe is CVE-2026-53727?

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-53727?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-53727?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-53727 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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