CVE-2019-18625

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-01-06 · updated 2026-06-17

Description

An issue was discovered in Suricata 5.0.0. It was possible to bypass/evade any tcp based signature by faking a closed TCP session using an evil server. After the TCP SYN packet, it is possible to inject a RST ACK and a FIN ACK packet with a bad TCP Timestamp option. The client will ignore the RST ACK and the FIN ACK packets because of the bad TCP Timestamp option. Both linux and windows client are ignoring the injected packets.

Affected products

Debian Linux: 8.0
OISF suricata: 5.0.0

References

https://github.com/OISF/suricata/commit/9f0294fadca3dcc18c919424242a41e01f3e8318
https://github.com/OISF/suricata/commit/ea0659de7640cf6a51de5bbd1dbbb0414e4623a0
https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html
https://redmine.openinfosecfoundation.org/issues/3286
https://redmine.openinfosecfoundation.org/issues/3395
https://github.com/OISF/suricata/commit/9f0294fadca3dcc18c919424242a41e01f3e8318
https://github.com/OISF/suricata/commit/ea0659de7640cf6a51de5bbd1dbbb0414e4623a0
https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html
https://redmine.openinfosecfoundation.org/issues/3286
https://redmine.openinfosecfoundation.org/issues/3395

Get alerted when CVE-2019-18625 or the next vulnerability affects your stack