MediumFix available
samba — security advisory
A vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module "acl_xattr" is configured with "acl_xattr:ignore system acls = yes". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.
- Products
- samba
- Affected versions
- Not specified
- Fixed versions
- 4.18.8-r0
- CVEs
- CVE-2023-4091
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 14:59 UTC · Revision 1
Source evidence
A vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module "acl_xattr" is configured with "acl_xattr:ignore system acls = yes". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.
osv:ALPINE-CVE-2023-4091
samba
Fixed versions: 4.18.8-r0
samba
Fixed versions: 4.18.8-r0
samba
Fixed versions: 4.18.8-r0
samba
Fixed versions: 4.18.8-r0
samba
Fixed versions: 4.18.8-r0
samba
Fixed versions: 4.18.8-r0
samba
Fixed versions: 4.18.8-r0
Complete source record
{
"id": "dcb6478d47bbdc809c5951abc3c79204b3ebc1c989111960876ec18da5c205d0",
"url": "https://osv.dev/vulnerability/ALPINE-CVE-2023-4091",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "ALPINE-CVE-2023-4091",
"summary": "A vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module \"acl_xattr\" is configured with \"acl_xattr:ignore system acls = yes\". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.",
"evidence": "osv:ALPINE-CVE-2023-4091",
"products": [
{
"name": {
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"evidence": "/affected/0/package/name"
},
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"evidence": "/affected/0/ranges"
}
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},
{
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{
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],
"severity": "medium",
"structured": {
"id": "ALPINE-CVE-2023-4091",
"aliases": [
"ALPINE-CVE-2023-4091"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"
}
],
"affected": [
{
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],
"package": {
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"purl": "pkg:apk/alpine/samba?arch=source",
"ecosystem": "Alpine:v3.18"
},
"database_specific": {
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},
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{
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"package": {
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"ecosystem": "Alpine:v3.19"
},
"database_specific": {
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{
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"package": {
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},
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"package": {
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"ecosystem": "Alpine:v3.22"
},
"database_specific": {
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},
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{
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],
"package": {
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"purl": "pkg:apk/alpine/samba?arch=source",
"ecosystem": "Alpine:v3.23"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2023-4091.json"
},
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},
{
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],
"package": {
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"purl": "pkg:apk/alpine/samba?arch=source",
"ecosystem": "Alpine:v3.24"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2023-4091.json"
},
"ecosystem_specific": {}
}
],
"modified": "2026-10-26T17:17:58.638310025Z",
"provider": "osv",
"upstream": [
"CVE-2023-4091"
],
"references": [
"https://security.alpinelinux.org/vuln/CVE-2023-4091"
]
},
"related_cves": [
{
"value": "CVE-2023-4091",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 454486,
"published_at": "2023-11-03T08:15:08.197+00:00"
}