# CVE-2026-31931: Suricata tls: null dereference in tls.alpn rule keyword

> A null pointer dereference in Suricata's tls.alpn rule keyword allows attackers to crash the service, requiring specific rule configuration.

- **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:** 2 Apr 2026
- **Updated:** 2 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-31931, GHSA-gr22-4784-xvw3, UBUNTU-CVE-2026-31931

## What is CVE-2026-31931?

CVE-2026-31931 is a high-severity vulnerability in Oisf Suricata, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Suricata is a network IDS, IPS and NSM engine. From version 8.0.0 to before version 8.0.4, use of the "tls.alpn" rule keyword can cause Suricata to crash with a NULL dereference. This issue has been patched in version 8.0.4.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-31931?

It affects 1 product.


Products: Oisf Suricata.

## How do I fix CVE-2026-31931?

Upgrade to a fixed version.

## Is CVE-2026-31931 being exploited?

There is no known exploitation of CVE-2026-31931 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-2026-31931 and fix it if it is affected.

What it is: CVE-2026-31931 is a high-severity vulnerability in Oisf Suricata, published on 2 Apr 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-2026-31931 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-2026-31931/ (Markdown: https://insights.sbomify.com/CVE-2026-31931/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31931
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31931
- OSV: https://osv.dev/vulnerability/CVE-2026-31931

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31931/
Summaries are generated and may contain mistakes; the official description above is the record.