# CVE-2021-45098: Security feature bypass in n/a

> Attackers can bypass HTTP-based signature detection in Suricata by injecting spoofed RST packets with random TCP MD5 options, allowing malicious traffic to evade inspection.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Dec 2021
- **Updated:** 3 Nov 2025
- **Also known as:** DEBIAN-CVE-2021-45098, GHSA-cfcf-x7x2-gpf8, UBUNTU-CVE-2021-45098

## What is CVE-2021-45098?

CVE-2021-45098 is a high-severity vulnerability in Debian Debian Linux, published on 16 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

## Which versions are affected by CVE-2021-45098?

It affects 2 products.


Products: Debian Debian Linux, Oisf Suricata.

## How do I fix CVE-2021-45098?

Upgrade to a fixed version.

## Is CVE-2021-45098 being exploited?

There is no known exploitation of CVE-2021-45098 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-45098 and fix it if it is affected.

What it is: CVE-2021-45098 is a high-severity vulnerability in Debian Debian Linux, published on 16 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-45098 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-45098/ (Markdown: https://insights.sbomify.com/CVE-2021-45098/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-45098
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-45098
- OSV: https://osv.dev/vulnerability/CVE-2021-45098

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-45098/
Summaries are generated and may contain mistakes; the official description above is the record.