linux — security advisory
An issue was discovered in the Linux kernel before 6.3.3. There is an out-of-bounds read in crc16 in lib/crc16.c when called from fs/ext4/super.c because ext4_group_desc_csum does not properly check an offset. NOTE: this is disputed by third parties because the kernel is not intended to defend against attackers with the stated "When modifying the block device while it is mounted by the filesystem" access.
- Products
- linux
- Affected versions
- 6.1.27-1
- Fixed versions
- 6.1.37-1, 6.3.7-1
- CVEs
- CVE-2023-34256
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 16:23 UTC · Revision 1
Source evidence
An issue was discovered in the Linux kernel before 6.3.3. There is an out-of-bounds read in crc16 in lib/crc16.c when called from fs/ext4/super.c because ext4_group_desc_csum does not properly check an offset. NOTE: this is disputed by third parties because the kernel is not intended to defend against attackers with the stated "When modifying the block device while it is mounted by the filesystem" access.
osv:DEBIAN-CVE-2023-34256
linux
Fixed versions: 6.1.37-1
linux
Fixed versions: 6.3.7-1
linux
Fixed versions: 6.3.7-1
Complete source record
{
"id": "2c35ebb50121052533684bdb88ae803ab80817fef1c6df61e2deb57a005c7df3",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2023-34256",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2023-34256",
"summary": "An issue was discovered in the Linux kernel before 6.3.3. There is an out-of-bounds read in crc16 in lib/crc16.c when called from fs/ext4/super.c because ext4_group_desc_csum does not properly check an offset. NOTE: this is disputed by third parties because the kernel is not intended to defend against attackers with the stated \"When modifying the block device while it is mounted by the filesystem\" access.",
"evidence": "osv:DEBIAN-CVE-2023-34256",
"products": [
{
"name": {
"value": "linux",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "6.1.37-1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "6.1.27-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "linux",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "6.3.7-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "linux",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "6.3.7-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2023-34256",
"aliases": [
"DEBIAN-CVE-2023-34256"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "6.1.37-1"
}
]
}
],
"package": {
"name": "linux",
"purl": "pkg:deb/debian/linux?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"6.1.27-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-34256.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "6.3.7-1"
}
]
}
],
"package": {
"name": "linux",
"purl": "pkg:deb/debian/linux?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-34256.json"
},
"ecosystem_specific": {
"urgency": "unimportant"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "6.3.7-1"
}
]
}
],
"package": {
"name": "linux",
"purl": "pkg:deb/debian/linux?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-34256.json"
},
"ecosystem_specific": {
"urgency": "unimportant"
}
}
],
"modified": "2026-10-26T18:03:05.171317077Z",
"provider": "osv",
"upstream": [
"CVE-2023-34256"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2023-34256"
]
},
"related_cves": [
{
"value": "CVE-2023-34256",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 457561,
"published_at": "2023-05-31T20:15:10.817+00:00"
}