What’s Vulnerable › Vulnerabilities

CVE-2021-28428

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-04-05 · updated 2026-06-17
• Weakness: CWE-434

Description

File upload vulnerability in HorizontCMS before 1.0.0-beta.3 via uploading a .htaccess and *.hello files using the Media Files upload functionality. The original file upload vulnerability (CVE-2020-27387) was remediated by restricting the PHP extensions; however, we confirmed that the filter was bypassed via uploading an arbitrary .htaccess and *.hello files in order to execute PHP code to gain RCE.

Affected products

• Horizontcms Project Horizontcms: 1.0.0, 1.0.0-alpha, 1.0.0-alpha2, 1.0.0-alpha3, 1.0.0-alpha4, 1.0.0-alpha5 (+5)

References

• https://github.com/ttimot24/HorizontCMS
• https://github.com/ttimot24/HorizontCMS/commit/9c4d6827cbe96decec6834d53660e14ab2bf8838
• https://github.com/ttimot24/HorizontCMS
• https://github.com/ttimot24/HorizontCMS/commit/9c4d6827cbe96decec6834d53660e14ab2bf8838

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