CVE-2026-44312: CWE-829: Inclusion of Functionality from Untrusted Control Sphere in premailer css_parser
The css_parser Ruby gem versions prior to 2.1.0 and 1.22.0 do not validate HTTPS certificates when loading stylesheets, accepting any certificate without verification. This allows a man-in-the-middle attacker to inject or modify CSS content by exploiting the lack of HTTPS certificate validation. The vulnerability is fixed in versions 2.1.0 and 1.22.
AI Analysis
Technical Summary
The css_parser gem for Ruby, used to parse CSS, establishes HTTPS connections with OpenSSL::SSL::VERIFY_NONE prior to versions 2.1.0 and 1.22.0. This means it does not validate the authenticity of HTTPS certificates, allowing an attacker positioned as a man-in-the-middle to inject or alter CSS content during stylesheet loading. This vulnerability is classified under CWE-829 (Inclusion of Functionality from Untrusted Control Sphere) and CWE-295 (Improper Certificate Validation). The issue is resolved in css_parser versions 2.1.0 and 1.22.0.
Potential Impact
An attacker capable of intercepting HTTPS traffic can modify or inject malicious CSS content due to the lack of certificate validation. This can lead to integrity issues in the CSS content loaded by applications using vulnerable versions of css_parser. There is no direct confidentiality or availability impact reported. The CVSS score is 5.8 (medium severity), reflecting the network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to integrity.
Mitigation Recommendations
Upgrade css_parser to version 2.1.0 or later, or 1.22.0 or later, where proper HTTPS certificate validation is implemented. No other mitigations are indicated as the vulnerability is fixed in these versions. Patch status is confirmed by the vendor advisory stating the fix is included in these releases.
CVE-2026-44312: CWE-829: Inclusion of Functionality from Untrusted Control Sphere in premailer css_parser
Description
The css_parser Ruby gem versions prior to 2.1.0 and 1.22.0 do not validate HTTPS certificates when loading stylesheets, accepting any certificate without verification. This allows a man-in-the-middle attacker to inject or modify CSS content by exploiting the lack of HTTPS certificate validation. The vulnerability is fixed in versions 2.1.0 and 1.22.
CVSS v3.1
Score 5.8medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The css_parser gem for Ruby, used to parse CSS, establishes HTTPS connections with OpenSSL::SSL::VERIFY_NONE prior to versions 2.1.0 and 1.22.0. This means it does not validate the authenticity of HTTPS certificates, allowing an attacker positioned as a man-in-the-middle to inject or alter CSS content during stylesheet loading. This vulnerability is classified under CWE-829 (Inclusion of Functionality from Untrusted Control Sphere) and CWE-295 (Improper Certificate Validation). The issue is resolved in css_parser versions 2.1.0 and 1.22.0.
Potential Impact
An attacker capable of intercepting HTTPS traffic can modify or inject malicious CSS content due to the lack of certificate validation. This can lead to integrity issues in the CSS content loaded by applications using vulnerable versions of css_parser. There is no direct confidentiality or availability impact reported. The CVSS score is 5.8 (medium severity), reflecting the network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to integrity.
Mitigation Recommendations
Upgrade css_parser to version 2.1.0 or later, or 1.22.0 or later, where proper HTTPS certificate validation is implemented. No other mitigations are indicated as the vulnerability is fixed in these versions. Patch status is confirmed by the vendor advisory stating the fix is included in these releases.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-05T19:00:06.022Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a05fd9fec166c07b0f93177
Added to database: 05/14/2026, 16:51:43 UTC
Last enriched: 05/22/2026, 15:34:42 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 72
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