Critical
Security advisory
An issue was discovered in Suricata 5.0.0. It is possible to bypass/evade any tcp based signature by overlapping a TCP segment with a fake FIN packet. The fake FIN packet is injected just before the PUSH ACK packet we want to bypass. The PUSH ACK packet (containing the data) will be ignored by Suricata because it overlaps the FIN packet (the sequence and ack number are identical in the two packets). The client will ignore the fake FIN packet because the ACK flag is not set. Both linux and windows clients are ignoring the injected packet.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2019-18792
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:28 UTC · Revision 1
Source evidence
An issue was discovered in Suricata 5.0.0. It is possible to bypass/evade any tcp based signature by overlapping a TCP segment with a fake FIN packet. The fake FIN packet is injected just before the PUSH ACK packet we want to bypass. The PUSH ACK packet (containing the data) will be ignored by Suricata because it overlaps the FIN packet (the sequence and ack number are identical in the two packets). The client will ignore the fake FIN packet because the ACK flag is not set. Both linux and windows clients are ignoring the injected packet.
osv:CVE-2019-18792
Complete source record
{
"id": "cbd3ff30f6e76e47dfd78082e6b2ebd4f5cf9e2be3ea915298a886c7f791b92d",
"url": "https://osv.dev/vulnerability/CVE-2019-18792",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2019-18792",
"summary": "An issue was discovered in Suricata 5.0.0. It is possible to bypass/evade any tcp based signature by overlapping a TCP segment with a fake FIN packet. The fake FIN packet is injected just before the PUSH ACK packet we want to bypass. The PUSH ACK packet (containing the data) will be ignored by Suricata because it overlaps the FIN packet (the sequence and ack number are identical in the two packets). The client will ignore the fake FIN packet because the ACK flag is not set. Both linux and windows clients are ignoring the injected packet.",
"evidence": "osv:CVE-2019-18792",
"products": [],
"severity": "critical",
"structured": {
"id": "CVE-2019-18792",
"aliases": [
"CVE-2019-18792"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/oisf/suricata",
"type": "GIT",
"events": [
{
"introduced": "45399567a65ea4ccbd84cee3638a1d2e61bdab4e"
},
{
"fixed": "c91a7ad9dc3192c9c59c9d9a1f63131f1da4782e"
},
{
"introduced": "697410cbbfe351afd307424bab5590955a1b95ae"
},
{
"last_affected": "697410cbbfe351afd307424bab5590955a1b95ae"
},
{
"fixed": "1c63d3905852f746ccde7e2585600b2199cefb4b"
},
{
"fixed": "fa692df37a796c3330c81988d15ef1a219afc006"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:oisf:suricata:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "4.1.5"
},
{
"fixed": "4.1.6"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:oisf:suricata:5.0.0:*:*:*:*:*:*:*",
"range": [
{
"introduced": "5.0.0"
},
{
"last_affected": "5.0.0"
}
],
"source": "CPE_STRING"
},
{
"range": [
{
"fixed": "1c63d3905852f746ccde7e2585600b2199cefb4b"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "fa692df37a796c3330c81988d15ef1a219afc006"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"5.0.0",
"suricata-4.1.5",
"suricata-5.0.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2019-18792.json",
"vanir_signatures": [
{
"id": "CVE-2019-18792-1a417d03",
"digest": {
"threshold": 0.9,
"line_hashes": [
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"221204083360005168731164196304212191593",
"21390434416426577672697603659514546199",
"241751286558114224891527998751973942008",
"315659100405804393893208892637684634774",
"7013461576087916721718213038207716288",
"51532122097456985586895166914441882440",
"46556905094042848375660928505030236932"
]
},
"source": "https://github.com/oisf/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b",
"target": {
"file": "src/stream-tcp.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
},
{
"id": "CVE-2019-18792-2c67d5b3",
"digest": {
"threshold": 0.9,
"line_hashes": [
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"21390434416426577672697603659514546199",
"241751286558114224891527998751973942008",
"315659100405804393893208892637684634774",
"7013461576087916721718213038207716288",
"51532122097456985586895166914441882440",
"46556905094042848375660928505030236932"
]
},
"source": "https://github.com/oisf/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006",
"target": {
"file": "src/stream-tcp.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
},
{
"id": "CVE-2019-18792-63f7cd2e",
"digest": {
"length": 4675,
"function_hash": "33221368742771496873975166895782756032"
},
"source": "https://github.com/oisf/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006",
"target": {
"file": "src/stream-tcp.c",
"function": "StreamTcpPacket"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2019-18792-c9346651",
"digest": {
"length": 2066,
"function_hash": "186385305067634872466018488430576115100"
},
"source": "https://github.com/oisf/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b",
"target": {
"file": "src/stream-tcp.c",
"function": "StreamTcpTest10"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2019-18792-d25a80a0",
"digest": {
"length": 2066,
"function_hash": "186385305067634872466018488430576115100"
},
"source": "https://github.com/oisf/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006",
"target": {
"file": "src/stream-tcp.c",
"function": "StreamTcpTest10"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2019-18792-eeaec1b8",
"digest": {
"length": 5058,
"function_hash": "16861237037782119358511266195933336500"
},
"source": "https://github.com/oisf/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b",
"target": {
"file": "src/stream-tcp.c",
"function": "StreamTcpPacket"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
}
],
"vanir_signatures_modified": "2026-10-24T14:50:54Z"
}
}
],
"modified": "2026-10-24T14:50:54.160265022Z",
"provider": "osv",
"references": [
"https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html",
"https://github.com/OISF/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b",
"https://github.com/OISF/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006",
"https://redmine.openinfosecfoundation.org/issues/3324",
"https://redmine.openinfosecfoundation.org/issues/3394"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*"
],
"vendor_product": "debian:debian_linux",
"extracted_events": [
{
"range": [
{
"introduced": "8.0"
},
{
"last_affected": "8.0"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2019-18792",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 443829,
"published_at": "2020-01-06T18:15:23.183+00:00"
}