Bug 2477502 (CVE-2026-44312)

Summary: CVE-2026-44312 css_parser: css_parser: Man-in-the-Middle attack due to improper HTTPS certificate validation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akostadi, amasferr, dmayorov, jlledo, pantinor, tsedmik
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the css_parser Ruby gem prior to 2.1.0 and 1.22.0. When stylesheets are fetched over HTTPS, connections are opened with OpenSSL::SSL::VERIFY_NONE, so certificate validation is skipped. A network MITM attacker can present an untrusted certificate and inject or modify CSS returned to the parser.
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Description OSIDB Bzimport 2026-05-14 17:02:16 UTC 
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.