CVE-2019-18792

CRITICAL

Suricata 5.0.0 - TCP Signature Bypass via Overlapping FIN Packet

Title source: llm
STIX 2.1

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.

References (5)

Core 5
Core References
Exploit, Third Party Advisory x_refsource_misc
https://redmine.openinfosecfoundation.org/issues/3324
Exploit, Third Party Advisory x_refsource_misc
https://redmine.openinfosecfoundation.org/issues/3394
Third Party Advisory mailing-list x_refsource_mlist
https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html

Scores

CVSS v3 9.1
EPSS 0.0252
EPSS Percentile 82.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Details

CWE
CWE-436
Status published
Products (3)
debian/debian_linux 8.0
oisf/suricata 5.0.0
oisf/suricata 4.1.5 - 4.1.6
Published Jan 06, 2020
Tracked Since Feb 18, 2026