CVE-2021-45098

Name: CVE-2021-45098
Creator: NVD / NIST
Published: 2021-12-16T05:15:08.727+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.82%

Last modified Jun 17, 2026

CVE-2021-45098 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 1.82% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.82%

76.0th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Oisf	Suricata	< 6.0.4
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0

References

https://forum.suricata.io/t/suricata-6-0-4-and-5-0-8-released/1942Release Notes, Vendor Advisory
https://github.com/OISF/suricata/commit/50e2b973eeec7172991bf8f544ab06fb782b97dfPatch, Third Party Advisory
https://github.com/OISF/suricata/releasesRelease Notes, Third Party Advisory
https://redmine.openinfosecfoundation.org/issues/4710Exploit, Issue Tracking, Patch, Vendor Advisory
https://forum.suricata.io/t/suricata-6-0-4-and-5-0-8-released/1942Release Notes, Vendor Advisory
https://github.com/OISF/suricata/commit/50e2b973eeec7172991bf8f544ab06fb782b97dfPatch, Third Party Advisory
https://github.com/OISF/suricata/releasesRelease Notes, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/03/msg00029.html
https://redmine.openinfosecfoundation.org/issues/4710Exploit, Issue Tracking, Patch, Vendor Advisory

Timeline

Published: Dec 16, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-45098?

How severe is CVE-2021-45098?

CVE-2021-45098 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.82% probability of exploitation in the next 30 days.

How do I fix CVE-2021-45098?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-45098?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST