CVE-2021-45098
An issue was discovered in Suricata before 6.0.4. It is possible to bypass/evade any HTTP-based...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
7.5
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.
- Record
CVE-2021-45098- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:P/A:N - Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2021-45098- Updated
- 2026-11-02
EUVDEUVD-2021-31889 No score
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.
- Record
EUVD-2021-31889- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-cfcf-x7x2-gpf8
7.5
An issue was discovered in Suricata before 6.0.4. It is possible to bypass/evade any HTTP-based...
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.
- Record
GHSA-cfcf-x7x2-gpf8- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVALPINE-CVE-2021-45098
7.5
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.
- Record
ALPINE-CVE-2021-45098- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-03
OSV
7.5
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.
- Record
CVE-2021-45098- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVDEBIAN-CVE-2021-45098
7.5
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.
- Record
DEBIAN-CVE-2021-45098- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-45098
7.5
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.
- Record
UBUNTU-CVE-2021-45098- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
suricataAlpine:v3.15 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.16 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.17 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.18 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.19 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.20 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.21 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.22 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.23 |
before 6.0.4-r0 | 6.0.4-r0 |
suricataAlpine:v3.24 |
before 6.0.4-r0 | 6.0.4-r0 |
Show 5 moreShow less
| Package | Affected | Fixed |
|---|---|---|
suricataDebian:13 |
before 1:6.0.4-1 | 1:6.0.4-1 |
suricataDebian:14 |
before 1:6.0.4-1 | 1:6.0.4-1 |
suricataDebian:11 From an advisory covering 7 CVEs |
before 1:6.0.1-3+deb11u1, plus listed versions 1:6.0.1-3 |
1:6.0.1-3+deb11u1 |
suricataUbuntu:16.04:LTS |
All versions, plus listed versions 2.0.8-1build12.0.9-12.0.10-12.0.10-22.0.11-13.0-1 |
None known |
suricataUbuntu:18.04:LTS |
All versions, plus listed versions 3.2-2ubuntu3 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| affected, aliases, references | OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-45098 is a high vulnerability (CVSS 7.5) in Oisf Suricata, published December 16, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.96%, the 80th percentile. Fixed in suricata 6.0.4-r0.
References
github.com/OISF/suricata/releases
redmine.openinfosecfoundation.org/issues/4710
forum.suricata.io/t/suricata-6-0-4-and-5-0-8-released/1942
github.com/OISF/suricata/commit/50e2b973eeec7172991bf8f544ab06fb782b97df
lists.debian.org/debian-lts-announce/2025/03/msg00029.html
nvd.nist.gov/vuln/detail/CVE-2021-45098