# CVE-2026-97666: Nexus Repository 3 - Unsafe Reflection in ExtDirect Repository Endpoint

> Unauthenticated attackers can determine the presence of specific Java classes in Sonatype Nexus Repository 3 via unsafe reflection in the ExtDirect endpoint.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-rchx-54gw-m94r

## What is CVE-2026-97666?

CVE-2026-97666 is a medium-severity vulnerability in Sonatype Nexus Repository 3, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Sonatype Nexus Repository 3 allows an unauthenticated remote attacker to supply attacker-controlled input to a Java class loading call through an ExtDirect endpoint. This allows the attacker to learn whether specific classes are present in the application. The issue does not by itself allow code execution.

Weakness: CWE-470 (Use of Externally-Controlled Input to Select Classes or Code)

## Which versions are affected by CVE-2026-97666?


## How do I fix CVE-2026-97666?

No fix has been published for CVE-2026-97666 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-97666 being exploited?

There is no known exploitation of CVE-2026-97666 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97666 and fix it if it is affected.

What it is: CVE-2026-97666 is a medium-severity vulnerability in Sonatype Nexus Repository 3, published on 15 Oct 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-2026-97666 in the wild and no public exploit code.

Affected product: Sonatype Nexus Repository 3. 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-2026-97666/ (Markdown: https://insights.sbomify.com/CVE-2026-97666/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97666
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97666
- OSV: https://osv.dev/vulnerability/CVE-2026-97666

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97666/
Summaries are generated and may contain mistakes; the official description above is the record.