High
modsecurity — security advisory
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 3.0.16, the multipart/form-data request body parser in libmodsecurity silently removes embedded line breaks from non-file form-field values before exporting them to ARGS and ARGS_POST because src/request_body_processor/multipart.cc overwrites reserved bytes in m_reserve instead of appending the current buffer. This creates a parser differential between ModSecurity and backend applications that preserve line breaks in form fields, allowing rules that inspect ARGS or ARGS_POST to miss payloads whose dangerous syntax depends on a line break. This issue is fixed in version 3.0.16.
- Products
- modsecurity
- Affected versions
- 3.0.10-1, 3.0.11-1, 3.0.12-1, 3.0.12-1.1build1, 3.0.12-1.1build2, 3.0.14-1build1, 3.0.14-1build2, 3.0.15-1, 3.0.16-1, 3.0.3-1, 3.0.4-1, 3.0.4-1build1, 3.0.4-2, 3.0.6-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-52747
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:28 UTC · Revision 1
Source evidence
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 3.0.16, the multipart/form-data request body parser in libmodsecurity silently removes embedded line breaks from non-file form-field values before exporting them to ARGS and ARGS_POST because src/request_body_processor/multipart.cc overwrites reserved bytes in m_reserve instead of appending the current buffer. This creates a parser differential between ModSecurity and backend applications that preserve line breaks in form fields, allowing rules that inspect ARGS or ARGS_POST to miss payloads whose dangerous syntax depends on a line break. This issue is fixed in version 3.0.16.
osv:UBUNTU-CVE-2026-52747
modsecurity
Fixed versions: Not specified
modsecurity
Fixed versions: Not specified
modsecurity
Fixed versions: Not specified
modsecurity
Fixed versions: Not specified
modsecurity
Fixed versions: Not specified
Complete source record
{
"id": "478aaacbeb5d13f5ddf43ea2ac75f3dc101f70a7e7f91d956d3bbad9369e4607",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-52747",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-52747",
"summary": "ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 3.0.16, the multipart/form-data request body parser in libmodsecurity silently removes embedded line breaks from non-file form-field values before exporting them to ARGS and ARGS_POST because src/request_body_processor/multipart.cc overwrites reserved bytes in m_reserve instead of appending the current buffer. This creates a parser differential between ModSecurity and backend applications that preserve line breaks in form fields, allowing rules that inspect ARGS or ARGS_POST to miss payloads whose dangerous syntax depends on a line break. This issue is fixed in version 3.0.16.",
"evidence": "osv:UBUNTU-CVE-2026-52747",
"products": [
{
"name": {
"value": "modsecurity",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.3-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.0.4-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.0.4-1build1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "modsecurity",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.4-2",
"evidence": "/affected/1/versions"
},
{
"value": "3.0.6-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "modsecurity",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.10-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.0.11-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.0.12-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.0.12-1.1build1",
"evidence": "/affected/2/versions"
},
{
"value": "3.0.12-1.1build2",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "modsecurity",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.14-1build2",
"evidence": "/affected/3/versions"
},
{
"value": "3.0.15-1",
"evidence": "/affected/3/versions"
},
{
"value": "3.0.16-1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "modsecurity",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.14-1build1",
"evidence": "/affected/4/versions"
},
{
"value": "3.0.14-1build2",
"evidence": "/affected/4/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-52747",
"aliases": [
"UBUNTU-CVE-2026-52747"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity",
"purl": "pkg:deb/ubuntu/modsecurity?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"3.0.3-1",
"3.0.4-1",
"3.0.4-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52747.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libmodsecurity3",
"binary_version": "3.0.4-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity",
"purl": "pkg:deb/ubuntu/modsecurity?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"3.0.4-2",
"3.0.6-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52747.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libmodsecurity3",
"binary_version": "3.0.6-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity",
"purl": "pkg:deb/ubuntu/modsecurity?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"3.0.10-1",
"3.0.11-1",
"3.0.12-1",
"3.0.12-1.1build1",
"3.0.12-1.1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52747.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libmodsecurity3t64",
"binary_version": "3.0.12-1.1build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity",
"purl": "pkg:deb/ubuntu/modsecurity?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"3.0.14-1build2",
"3.0.15-1",
"3.0.16-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52747.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libmodsecurity3t64",
"binary_version": "3.0.16-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity",
"purl": "pkg:deb/ubuntu/modsecurity?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"3.0.14-1build1",
"3.0.14-1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-52747.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libmodsecurity3t64",
"binary_version": "3.0.14-1build2"
}
]
}
}
],
"modified": "2026-10-17T12:58:34.215044834Z",
"provider": "osv",
"upstream": [
"CVE-2026-52747"
],
"references": [
"https://ubuntu.com/security/CVE-2026-52747",
"https://www.cve.org/CVERecord?id=CVE-2026-52747",
"https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-rcw9-2f5r-7p88",
"https://github.com/owasp-modsecurity/ModSecurity/commit/875504c2758169c41be1ad2f0cc64d896b7815d7",
"https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.16"
]
},
"related_cves": [
{
"value": "CVE-2026-52747",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 358796,
"published_at": "2026-07-10T22:16:00+00:00"
}