# CVE-2026-47843: Reactor Netty may incorrectly route traffic due to DNS resolver reuse

> Reactor Netty may reuse DNS resolvers across clients, potentially allowing traffic routing to unintended hosts in multi-client scenarios.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/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:** 26 Aug 2026
- **Updated:** 26 Aug 2026
- **Also known as:** CLEANSTART-2026-CL63424, CLEANSTART-2026-FI75370, CLEANSTART-2026-GW15046, CLEANSTART-2026-IJ88105, CLEANSTART-2026-UA66852, GHSA-7f23-wcwg-2f8r

## What is CVE-2026-47843?

CVE-2026-47843 is a low-severity server-side request forgery vulnerability in Spring Reactor Netty, published on 26 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In specific scenarios involving multiple clients with different DNS resolver configurations, Reactor Netty may incorrectly reuse a previously configured DNS resolver.
Reactor Netty 1.3.0 - 1.3.6
Reactor Netty 1.1.0 - 1.2.18
Reactor Netty 1.0.52 and earlier

## Which versions are affected by CVE-2026-47843?

It affects 1 product.


Products: Broadcom Reactor Netty.

## How do I fix CVE-2026-47843?

Upgrade to a fixed version.

## Is CVE-2026-47843 being exploited?

There is no known exploitation of CVE-2026-47843 in the wild and no public exploit code.

## Other vulnerabilities in Spring Reactor Netty

- [CVE-2023-34062](https://insights.sbomify.com/CVE-2023-34062/): In Reactor Netty HTTP Server a malicious user can send a request using a specially crafted URL that can lead to a directory traversal attack (high 7.5)
- [CVE-2019-11284](https://insights.sbomify.com/CVE-2019-11284/): Reactor Netty authentication leak in redirects (medium 6.8)
- [CVE-2020-5403](https://insights.sbomify.com/CVE-2020-5403/): DoS Via Malformed URL with Reactor Netty HTTP Server (medium 6.5)
- [CVE-2020-5404](https://insights.sbomify.com/CVE-2020-5404/): Authentication Leak On Redirect With Reactor Netty HttpClient (medium 6.5)
- [CVE-2026-47848](https://insights.sbomify.com/CVE-2026-47848/): Reactor Netty WebSocket Client Leaks Credentials On Redirect (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-47843 and fix it if it is affected.

What it is: CVE-2026-47843 is a low-severity server-side request forgery vulnerability in Spring Reactor Netty, published on 26 Aug 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-2026-47843 in the wild and no public exploit code.

Affected product: Spring Reactor Netty. 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-2026-47843/ (Markdown: https://insights.sbomify.com/CVE-2026-47843/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-47843
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-47843
- OSV: https://osv.dev/vulnerability/CVE-2026-47843

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-47843/
Summaries are generated and may contain mistakes; the official description above is the record.