# CVE-2026-71418: Suricata doh2: crafted HTTP/2 DATA frames can cause quadratic CPU consumption

> Attackers can cause denial of service in Suricata by sending crafted HTTP/2 DATA frames that trigger quadratic CPU consumption during DNS-over-HTTP/2 processing.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-71418, GHSA-xjgq-3qw4-jp5f, UBUNTU-CVE-2026-71418

## What is CVE-2026-71418?

CVE-2026-71418 is a high-severity denial of service vulnerability in Oisf Suricata, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Suricata is a network Intrusion Detection System, Intrusion Prevention System and Network Security Monitoring engine. From 8.0.0 until 8.0.6, DNS-over-HTTP/2 processing in rust/src/http2/http2.rs retains previously processed HTTP/2 DATA frame contents instead of clearing the internal buffer. Multiple DATA frames with the EndOfStream flag set can grow the buffer to its 65 KiB limit while causing all prior contents to be processed again, producing quadratic CPU complexity, degraded packet processing, loss of monitoring visibility, or denial of service. This issue is fixed in version 8.0.6.

Weakness: CWE-407 (Inefficient Algorithmic Complexity)

## Which versions are affected by CVE-2026-71418?

It affects 1 product.


Products: Oisf Suricata.

## How do I fix CVE-2026-71418?

Upgrade to a fixed version.

## Is CVE-2026-71418 being exploited?

There is no known exploitation of CVE-2026-71418 in the wild and no public exploit code.

## Other vulnerabilities in Oisf Suricata

- [CVE-2023-35853](https://insights.sbomify.com/CVE-2023-35853/): Code injection in n/a (critical 9.8)
- [CVE-2021-37592](https://insights.sbomify.com/CVE-2021-37592/): Other in n/a (critical 9.8)
- [CVE-2018-10244](https://insights.sbomify.com/CVE-2018-10244/): Integer overflow in n/a (critical 9.8)
- [CVE-2026-94083](https://insights.sbomify.com/CVE-2026-94083/): Memory corruption in Suricata (critical 9.4)
- [CVE-2026-94084](https://insights.sbomify.com/CVE-2026-94084/): Use after free in Suricata (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71418 and fix it if it is affected.

What it is: CVE-2026-71418 is a high-severity denial of service vulnerability in Oisf Suricata, published on 18 Sep 2026. 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-2026-71418 in the wild and no public exploit code.

Affected product: Oisf Suricata. 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-2026-71418/ (Markdown: https://insights.sbomify.com/CVE-2026-71418/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71418
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71418
- OSV: https://osv.dev/vulnerability/CVE-2026-71418

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-71418/
Summaries are generated and may contain mistakes; the official description above is the record.