Description
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.
Published: 2026-05-14
Score: 5.8 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Github GHSA Github GHSA GHSA-ff6c-w6qf-7xqc CSS Parser: Improper Certificate Validation allows MITM injection of remote CSS content
History

Fri, 15 May 2026 18:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 15 May 2026 11:45:00 +0000

Type Values Removed Values Added
First Time appeared Premailer
Premailer css Parser
Vendors & Products Premailer
Premailer css Parser

Thu, 14 May 2026 17:00:00 +0000

Type Values Removed Values Added
Description 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.
Title css_parser allows to MITM included https css urls
Weaknesses CWE-295
CWE-829
References
Metrics cvssV3_1

{'score': 5.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N'}


Subscriptions

Premailer Css Parser
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-15T18:05:54.862Z

Reserved: 2026-05-05T19:00:06.022Z

Link: CVE-2026-44312

cve-icon Vulnrichment

Updated: 2026-05-15T18:03:38.497Z

cve-icon NVD

Status : Deferred

Published: 2026-05-14T17:16:22.393

Modified: 2026-05-15T19:16:59.240

Link: CVE-2026-44312

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-15T11:21:12Z

Weaknesses