Medium
fastnetmon — security advisory
FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read vulnerability in the NetFlow v9 data flowset processor. In src/netflow_plugin/netflow_v9_collector.cpp, the Data template branch (lines 1695-1702) iterates over flow records without performing a per-iteration bounds check against the packet end pointer. In contrast, the Options template branch (lines 1709-1719) correctly checks 'if (pkt + offset + field_template->total_length > packet_end)' before each iteration. The Data branch omits this check entirely. Since template definitions are sent by the network peer (and are unauthenticated UDP), an attacker can craft templates that cause the parser to read arbitrary memory past the packet buffer. This can leak sensitive memory contents or cause a crash.
- Products
- fastnetmon
- Affected versions
- 1.1.3+dfsg-3, 1.1.3+dfsg-4, 1.1.3+dfsg-6build1, 1.1.4-1, 1.1.4-1build3, 1.1.4-1build4, 1.1.4-1build5, 1.1.4-1ubuntu0.1~esm1, 1.2.5-1, 1.2.6-1, 1.2.6-1build1, 1.2.6-1build2, 1.2.6-1build3, 1.2.6-1build4, 1.2.6-1ubuntu0.1~esm1, 1.2.8+git20250911-1, 1.2.8+git20250911-1build1, 1.2.8+git20250911-1build2, 1.2.8+git20250911-2, 1.2.8+git20250911-2ubuntu0.1~esm1, 1.2.8-1build1, 1.2.8-1build2, 1.2.9-1, 1.2.9-1build1, 1.2.9-1build2
- Fixed versions
- Not specified
- CVEs
- CVE-2026-48683
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:21 UTC · Revision 1
Source evidence
FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read vulnerability in the NetFlow v9 data flowset processor. In src/netflow_plugin/netflow_v9_collector.cpp, the Data template branch (lines 1695-1702) iterates over flow records without performing a per-iteration bounds check against the packet end pointer. In contrast, the Options template branch (lines 1709-1719) correctly checks 'if (pkt + offset + field_template->total_length > packet_end)' before each iteration. The Data branch omits this check entirely. Since template definitions are sent by the network peer (and are unauthenticated UDP), an attacker can craft templates that cause the parser to read arbitrary memory past the packet buffer. This can leak sensitive memory contents or cause a crash.
osv:UBUNTU-CVE-2026-48683
fastnetmon
Fixed versions: Not specified
fastnetmon
Fixed versions: Not specified
fastnetmon
Fixed versions: Not specified
fastnetmon
Fixed versions: Not specified
fastnetmon
Fixed versions: Not specified
fastnetmon
Fixed versions: Not specified
Complete source record
{
"id": "3af5a79b893131c0823fdc60664ce78c43b8db9b76ca41b8bc2cfb21c64b41d3",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-48683",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-48683",
"summary": "FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read vulnerability in the NetFlow v9 data flowset processor. In src/netflow_plugin/netflow_v9_collector.cpp, the Data template branch (lines 1695-1702) iterates over flow records without performing a per-iteration bounds check against the packet end pointer. In contrast, the Options template branch (lines 1709-1719) correctly checks 'if (pkt + offset + field_template->total_length > packet_end)' before each iteration. The Data branch omits this check entirely. Since template definitions are sent by the network peer (and are unauthenticated UDP), an attacker can craft templates that cause the parser to read arbitrary memory past the packet buffer. This can leak sensitive memory contents or cause a crash.",
"evidence": "osv:UBUNTU-CVE-2026-48683",
"products": [
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{
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"evidence": "/affected/4/versions"
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{
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{
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{
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{
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{
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"evidence": "/affected/5/versions"
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{
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"evidence": "/affected/5/versions"
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{
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],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-48683",
"aliases": [
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],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
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"package": {
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"purl": "pkg:deb/ubuntu/fastnetmon?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
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"1.1.3+dfsg-4",
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],
"database_specific": {
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},
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"package": {
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"purl": "pkg:deb/ubuntu/fastnetmon?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
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],
"modified": "2026-10-17T12:58:30.819374933Z",
"provider": "osv",
"upstream": [
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],
"references": [
"https://ubuntu.com/security/CVE-2026-48683",
"https://www.cve.org/CVERecord?id=CVE-2026-48683",
"https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48683-netflow-v9-data-oob",
"https://github.com/pavel-odintsov/fastnetmon/commit/aa1069abaa8624e50b5d0c6c8ccd0f5d9ddc111e",
"https://github.com/pavel-odintsov/fastnetmon/pull/1057",
"https://github.com/pavel-odintsov/fastnetmon",
"https://github.com/pavel-odintsov/fastnetmon/blob/master/src/netflow_plugin/netflow_v9_collector.cpp"
]
},
"related_cves": [
{
"value": "CVE-2026-48683",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 358681,
"published_at": "2026-05-26T16:16:00+00:00"
}