CVE-2026-44312
css_parser allows to MITM included https css urls
CVSS Score
5.8
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-829 CWE-295 |
| Vendor | premailer |
| Product | css_parser |
| Published | May 14, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
premailer / css_parser
>= 2.0.0, < 2.1.0 < 1.22.0
References
github.com: https://github.com/premailer/css_parser/security/advisories/GHSA-ff6c-w6qf-7xqc github.com: https://github.com/premailer/css_parser/issues/185 github.com: https://github.com/premailer/css_parser/commit/35e689c904225add78e0c488cf04bad052666449 github.com: https://github.com/premailer/css_parser/commit/e0c95d5abe91b237becb90ff316531a6547ada18