Critical
Security advisory
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-28428
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 11:43 UTC · Revision 1
Source evidence
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.
osv:CVE-2021-28428
Complete source record
{
"id": "c9f9664395d8ccda262a56c0095934c9a35fb211edc6299cee6d331c222e15e2",
"url": "https://osv.dev/vulnerability/CVE-2021-28428",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2021-28428",
"summary": "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.",
"evidence": "osv:CVE-2021-28428",
"products": [],
"severity": "critical",
"structured": {
"id": "CVE-2021-28428",
"aliases": [
"CVE-2021-28428"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/ttimot24/horizont-cms",
"type": "GIT",
"events": [
{
"introduced": "3b09e6fbddf193fbd904b9f0cb72dc9dda252001"
},
{
"last_affected": "5aa34ac4e457a49b83f24a2969593c495f3ed9ad"
},
{
"fixed": "9c4d6827cbe96decec6834d53660e14ab2bf8838"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:-:*:*:*:*:*:*",
"range": [
{
"introduced": "1.0.0-NA"
},
{
"last_affected": "1.0.0-NA"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha:*:*:*:*:*:*",
"range": [
{
"introduced": "1.0.0-alpha"
},
{
"last_affected": "1.0.0-alpha"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:beta:*:*:*:*:*:*",
"range": [
{
"introduced": "1.0.0-beta"
},
{
"last_affected": "1.0.0-beta"
}
],
"source": "CPE_STRING"
},
{
"range": [
{
"fixed": "9c4d6827cbe96decec6834d53660e14ab2bf8838"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"1.0.0-NA",
"1.0.0-alpha",
"1.0.0-beta"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-28428.json"
}
}
],
"modified": "2026-10-20T10:54:35.957783693Z",
"provider": "osv",
"references": [
"https://github.com/ttimot24/HorizontCMS/commit/9c4d6827cbe96decec6834d53660e14ab2bf8838",
"https://github.com/ttimot24/HorizontCMS"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha2:*:*:*:*:*:*",
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha3:*:*:*:*:*:*",
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha4:*:*:*:*:*:*",
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha5:*:*:*:*:*:*",
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha6:*:*:*:*:*:*",
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha7:*:*:*:*:*:*",
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:alpha8:*:*:*:*:*:*",
"cpe:2.3:a:horizontcms_project:horizontcms:1.0.0:beta2:*:*:*:*:*:*"
],
"vendor_product": "horizontcms_project:horizontcms",
"extracted_events": [
{
"range": [
{
"introduced": "1.0.0-alpha2"
},
{
"last_affected": "1.0.0-alpha2"
},
{
"introduced": "1.0.0-alpha3"
},
{
"last_affected": "1.0.0-alpha3"
},
{
"introduced": "1.0.0-alpha4"
},
{
"last_affected": "1.0.0-alpha4"
},
{
"introduced": "1.0.0-alpha5"
},
{
"last_affected": "1.0.0-alpha5"
},
{
"introduced": "1.0.0-alpha6"
},
{
"last_affected": "1.0.0-alpha6"
},
{
"introduced": "1.0.0-alpha7"
},
{
"last_affected": "1.0.0-alpha7"
},
{
"introduced": "1.0.0-alpha8"
},
{
"last_affected": "1.0.0-alpha8"
},
{
"introduced": "1.0.0-beta2"
},
{
"last_affected": "1.0.0-beta2"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2021-28428",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 385700,
"published_at": "2022-04-05T16:15:11.88+00:00"
}