CVE-2021-28428

9.8 criticalEPSS 1.2%

Critical (9.8) in horizontcms project horizontcms. EPSS 1.2% chance of exploitation in the next 30 days.

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.

Severity

CVSS 3.1

9.8 critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 1.2% chance of exploitation in the next 30 days; higher than 69% of CVEs (scores of 2026-10-31)
CWE: CWE-434
Published: 2022-04-05
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

horizontcms_project:horizontcms

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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