CVE-2019-18792
It is possible to bypass/evade any tcp based signature by overlapping a TCP segment with a fake FIN packet.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.52%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- EPSS
- 2.52% probability · 85th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-436
- Affected
- oisf/suricata · debian/debian linux
- Source
- cve@mitre.org
EPSS 2.5% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/OISF/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4bPatch, Third Party Advisory
- https://github.com/OISF/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2020/01/msg00032.htmlThird Party Advisory
- https://redmine.openinfosecfoundation.org/issues/3324Exploit, Third Party Advisory
- https://redmine.openinfosecfoundation.org/issues/3394Exploit, Third Party Advisory
- https://github.com/OISF/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4bPatch, Third Party Advisory
- https://github.com/OISF/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006Patch, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2020/01/msg00032.htmlThird Party Advisory
- https://redmine.openinfosecfoundation.org/issues/3324Exploit, Third Party Advisory
- https://redmine.openinfosecfoundation.org/issues/3394Exploit, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.