Improper Certificate Validation Affecting ruby-css-parser package, versions <1.6.0-2+deb12u1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN12-RUBYCSSPARSER-16748494
- published18 May 2026
- disclosed14 May 2026
Introduced: 14 May 2026
CVE-2026-44312 (opens in a new tab)How to fix?
Upgrade Debian:12 ruby-css-parser to version 1.6.0-2+deb12u1 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:12 relevant fixed versions and status.
css_parser is a Ruby CSS parser. Prior to 2.1.0 and 1.22.0, the CSS Parser gem does not validate HTTPS connections, allowing a Man-in-the-Middle (MITM) attacker to inject or modify CSS content when stylesheets are loaded via HTTPS. The connection is established with OpenSSL::SSL::VERIFY_NONE, meaning any HTTPS certificate—even entirely untrusted—will be accepted without validation. This vulnerability is fixed in 2.1.0 and 1.22.0.
References
- https://security-tracker.debian.org/tracker/CVE-2026-44312
- https://github.com/premailer/css_parser/commit/35e689c904225add78e0c488cf04bad052666449
- https://github.com/premailer/css_parser/commit/e0c95d5abe91b237becb90ff316531a6547ada18
- https://github.com/premailer/css_parser/issues/185
- https://github.com/premailer/css_parser/security/advisories/GHSA-ff6c-w6qf-7xqc