High
modsecurity-crs — security advisory
The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.9 and 4.25.0, a bypass was identified in OWASP CRS that allows uploading files with dangerous extensions (.php, .phar, .jsp, .jspx) by inserting whitespace padding in the filename (e.g. photo. php or shell.jsp ). The affected rules do not normalize whitespace before evaluating the file extension regex, so the dot-extension check fails to match. This issue has been patched in versions 3.3.9 and 4.25.0.
- Products
- modsecurity-crs
- Affected versions
- 2.2.9-1, 3.0.0-3, 3.0.2-1, 3.1.1-1, 3.2.0-1, 3.3.0-1, 3.3.2-1, 3.3.5-1, 3.3.5-2, 3.3.7-1, 3.3.8-1, 3.3.9-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-33691
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:59 UTC · Revision 1
Source evidence
The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.9 and 4.25.0, a bypass was identified in OWASP CRS that allows uploading files with dangerous extensions (.php, .phar, .jsp, .jspx) by inserting whitespace padding in the filename (e.g. photo. php or shell.jsp ). The affected rules do not normalize whitespace before evaluating the file extension regex, so the dot-extension check fails to match. This issue has been patched in versions 3.3.9 and 4.25.0.
osv:UBUNTU-CVE-2026-33691
modsecurity-crs
Fixed versions: Not specified
modsecurity-crs
Fixed versions: Not specified
modsecurity-crs
Fixed versions: Not specified
modsecurity-crs
Fixed versions: Not specified
modsecurity-crs
Fixed versions: Not specified
modsecurity-crs
Fixed versions: Not specified
modsecurity-crs
Fixed versions: Not specified
modsecurity-crs
Fixed versions: Not specified
Complete source record
{
"id": "8b8d54bab049ff7ac5adf1c234659a548c32af28c831de3ebd4dbc0852582e3c",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-33691",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-33691",
"summary": "The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.9 and 4.25.0, a bypass was identified in OWASP CRS that allows uploading files with dangerous extensions (.php, .phar, .jsp, .jspx) by inserting whitespace padding in the filename (e.g. photo. php or shell.jsp ). The affected rules do not normalize whitespace before evaluating the file extension regex, so the dot-extension check fails to match. This issue has been patched in versions 3.3.9 and 4.25.0.",
"evidence": "osv:UBUNTU-CVE-2026-33691",
"products": [
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.2.9-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.0-3",
"evidence": "/affected/1/versions"
},
{
"value": "3.0.2-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.1.1-1",
"evidence": "/affected/2/versions"
},
{
"value": "3.2.0-1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.3.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "3.3.2-1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.3.5-1",
"evidence": "/affected/4/versions"
},
{
"value": "3.3.5-2",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.3.7-1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.3.8-1",
"evidence": "/affected/6/versions"
},
{
"value": "3.3.9-1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "modsecurity-crs",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.3.7-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.3.8-1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-33691",
"aliases": [
"UBUNTU-CVE-2026-33691"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/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:U/C:N/I:H/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"2.2.9-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "2.2.9-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"3.0.0-3",
"3.0.2-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "3.0.2-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"3.1.1-1",
"3.2.0-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "3.2.0-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"3.3.0-1",
"3.3.2-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "3.3.2-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"3.3.5-1",
"3.3.5-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "3.3.5-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"3.3.7-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "3.3.7-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"3.3.8-1",
"3.3.9-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "3.3.9-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "modsecurity-crs",
"purl": "pkg:deb/ubuntu/modsecurity-crs?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"3.3.7-1",
"3.3.8-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33691.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "modsecurity-crs",
"binary_version": "3.3.8-1"
}
]
}
}
],
"modified": "2026-10-17T13:00:00.472594812Z",
"provider": "osv",
"upstream": [
"CVE-2026-33691"
],
"references": [
"https://ubuntu.com/security/CVE-2026-33691",
"https://www.cve.org/CVERecord?id=CVE-2026-33691",
"https://github.com/coreruleset/coreruleset/security/advisories/GHSA-rw5f-9w43-gv2w"
]
},
"related_cves": [
{
"value": "CVE-2026-33691",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 360105,
"published_at": "2026-04-02T16:16:00+00:00"
}