# CVE-2026-54609: QTINeon has unauthenticated relay-to-host amplification via unbounded RECONNECT_REQUEST forwarding

> An unauthenticated attacker can cause denial of service on the host by exploiting unbounded packet forwarding in the QTINeon relay library.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** No
- **Published:** 28 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** GHSA-85rg-p3fr-xc2f, PYSEC-2026-3615

## What is CVE-2026-54609?

CVE-2026-54609 is a high-severity denial of service vulnerability in Quiet-Terminal-Interactive QTINeon, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

QTI Neon is a minimal, game-agnostic, relay-based UDP multiplayer protocol library. In version 1.0.0, the relay's handleReconnectRequest forwards RECONNECT_REQUEST packets to the host without bounding them, so an unauthenticated client can drive relay-to-host amplification and cause a denial of service on the host. No fixed version is available as of this review.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-406 (Insufficient Control of Network Message Volume (Network Amplification)), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-54609?

7 open source packages ship an affected version, including qti-neon and com.quietterminal:qti-neon.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `qti-neon` | PyPI | All versions | None |
| `qti-neon` | PyPI | All versions | None |
| `qti-neon` | PyPI | All versions | None |
| `qti-neon` | npm | All versions | None |
| `qti-neon` | npm | All versions | None |
| `com.quietterminal:qti-neon` | Maven | All versions | None |
| `com.quietterminal:qti-neon` | Maven | All versions | None |

## How do I fix CVE-2026-54609?

No fix has been published for CVE-2026-54609 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-54609 being exploited?

There is no known exploitation of CVE-2026-54609 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54609 and fix it if it is affected.

What it is: CVE-2026-54609 is a high-severity denial of service vulnerability in Quiet-Terminal-Interactive QTINeon, published on 28 Jul 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-2026-54609 in the wild and no public exploit code.

Affected packages and fixed versions:
- qti-neon (PyPI): affected all versions; no fix listed
- qti-neon (PyPI): affected all versions; no fix listed
- qti-neon (PyPI): affected all versions; no fix listed
- qti-neon (npm): affected all versions; no fix listed
- qti-neon (npm): affected all versions; no fix listed
- com.quietterminal:qti-neon (Maven): affected all versions; no fix listed
- com.quietterminal:qti-neon (Maven): affected all versions; no fix listed

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-2026-54609/ (Markdown: https://insights.sbomify.com/CVE-2026-54609/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54609
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54609
- OSV: https://osv.dev/vulnerability/CVE-2026-54609

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54609/
Summaries are generated and may contain mistakes; the official description above is the record.