Medium 5.8Published May 14, 2026

CVE-2026-44312css_parser allows to MITM included https css urls

Updated under an hour ago (Oct 28, 2026, 1:00 AM ET)

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It affects premailer css_parser. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for premailer css_parser

Exploited in the last 30 days

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.

CVSS: 5.8 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Weakness (CWE): CWE-829, CWE-295
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: May 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

premailer css_parser premailer:css_parser (from the name)	from 2.0.0, < 2.1.0; before 1.22.0	CNA record

References

References

https://github.com/premailer/css_parser/security/advisories/GHSA-ff6c-w6qf-7xqc	x-refsource-confirm
https://github.com/premailer/css_parser/issues/185	x-refsource-misc
https://github.com/premailer/css_parser/commit/35e689c904225add78e0c488cf04bad052666449	x-refsource-misc
https://github.com/premailer/css_parser/commit/e0c95d5abe91b237becb90ff316531a6547ada18	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.