What’s Vulnerable › Vulnerabilities

CVE-2021-45098

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.0% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-12-16 · updated 2026-06-17

Description

An issue was discovered in Suricata before 6.0.4. It is possible to bypass/evade any HTTP-based signature by faking an RST TCP packet with random TCP options of the md5header from the client side. After the three-way handshake, it's possible to inject an RST ACK with a random TCP md5header option. Then, the client can send an HTTP GET request with a forbidden URL. The server will ignore the RST ACK and send the response HTTP packet for the client's request. These packets will not trigger a Suricata reject action.

Affected products

• Debian Linux: 9.0, 10.0, 11.0
• OISF suricata: before 6.0.4 — fixed in 6.0.4

How to fix

Upgrade to a fixed version: OISF suricata 6.0.4. Check the vendor advisory for mitigations.

References

• https://forum.suricata.io/t/suricata-6-0-4-and-5-0-8-released/1942
• https://github.com/OISF/suricata/commit/50e2b973eeec7172991bf8f544ab06fb782b97df
• https://github.com/OISF/suricata/releases
• https://redmine.openinfosecfoundation.org/issues/4710
• https://forum.suricata.io/t/suricata-6-0-4-and-5-0-8-released/1942
• https://github.com/OISF/suricata/commit/50e2b973eeec7172991bf8f544ab06fb782b97df
• https://github.com/OISF/suricata/releases
• https://lists.debian.org/debian-lts-announce/2025/03/msg00029.html
• https://redmine.openinfosecfoundation.org/issues/4710

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