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Vulnerability record · CVE-2019-18792 · published 6 January 2020

CVE-2019-18792: Oisf suricata interpretation conflict vulnerability

Oisf · Suricata

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.

9.1 CVSS 3.1 Critical EPSS 2.5% · top 15.8% CWE-436 · Interpretation conflict
9.1CVSS 3.1 base score, v2 6.4
2.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
10References, 4 tagged exploit
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/OISF/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b PatchThird Party Advisory
https://github.com/OISF/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html Third Party Advisory
https://redmine.openinfosecfoundation.org/issues/3324 ExploitThird Party Advisory
https://redmine.openinfosecfoundation.org/issues/3394 ExploitThird Party Advisory
https://github.com/OISF/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b PatchThird Party Advisory
https://github.com/OISF/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html Third Party Advisory
https://redmine.openinfosecfoundation.org/issues/3324 ExploitThird Party Advisory
https://redmine.openinfosecfoundation.org/issues/3394 ExploitThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2019-18792), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.