# CVE-2026-18638: Velociraptor server crash via the SetPassword API

> Authenticated users can crash the Velociraptor server by calling SetPassword with a non-existent username, causing a denial of service.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Aug 2026
- **Updated:** 11 Aug 2026
- **Also known as:** GHSA-79v4-qf48-mh94

## What is CVE-2026-18638?

CVE-2026-18638 is a medium-severity denial of service vulnerability in Rapid7 Velociraptor, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Any authenticated Velociraptor user — including one holding only the readerrole — can terminate the entire server process with a single request, by calling SetPassword with a username that does not exist.

Weakness: CWE-703 (Improper Check or Handling of Exceptional Conditions), CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-18638?


## How do I fix CVE-2026-18638?

Apply the vendor's patch.

## Is CVE-2026-18638 being exploited?

There is no known exploitation of CVE-2026-18638 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18638 and fix it if it is affected.

What it is: CVE-2026-18638 is a medium-severity denial of service vulnerability in Rapid7 Velociraptor, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-18638 in the wild and no public exploit code.

Affected product: Rapid7 Velociraptor. 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-2026-18638/ (Markdown: https://insights.sbomify.com/CVE-2026-18638/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18638
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18638
- OSV: https://osv.dev/vulnerability/CVE-2026-18638

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18638/
Summaries are generated and may contain mistakes; the official description above is the record.