---
id: "GHSA-5rw2-6x5m-v22x"
kind: "vulnerability"
aliases: ["GHSA-5rw2-6x5m-v22x"]
title: "CVE-2026-94450 - Potential denial of service when configured to send Retry packets in s2n-quic"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["aws", "lab-disclosure", "package", "quic", "rust", "s2n-quic", "self-hosted"]
not_affected_if: ["aws-managed-services", "client-only", "default-config"]
published_at: "2026-09-22T00:00:00+00:00"
first_seen_at: "2026-10-24T19:28:16+00:00"
updated_at: "2026-10-25T05:30:26+00:00"
sources: [{"source": "lab", "url": "https://aws.amazon.com/security/security-bulletins/rss/2026-116-aws/", "first_seen_at": "2026-10-24T19:28:16+00:00"}]
---

# CVE-2026-94450 - Potential denial of service when configured to send Retry packets in s2n-quic

s2n-quic, AWS's Rust QUIC library, fails to validate Destination Connection ID length when a server is configured to send Retry packets. An unauthenticated attacker can shut down a server endpoint with a single crafted UDP datagram.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the s2n-quic version in Cargo.lock: `grep -A1 'name = "s2n-quic"' Cargo.lock`
- Check whether the server sets a Retry token or address validation option in its s2n-quic endpoint configuration (unknown which option name the sources use)

## Fix

- Upgrade s2n-quic to `1.89.0` or later
- Patch any forked or derivative copies of s2n-quic with the upstream fix
- No workaround exists; upgrading is the remediation

## Timeline

- 2026-10-24T19:28:16+00:00 lab https://aws.amazon.com/security/security-bulletins/rss/2026-116-aws/ — AWS: CVE-2026-94450 - Potential denial of service when configured to send Retry packets in s2n-quic

## Documents

- [advisory] AWS: CVE-2026-94450 - Potential denial of service when configured to send Retry packets in s2n-quic https://aws.amazon.com/security/security-bulletins/rss/2026-116-aws/

## From the sources

CVE-2026-94450 - Potential denial of service when configured to send Retry packets in s2n-quic

### CVE-2026-94450 - Potential denial of service when configured to send Retry packets in s2n-quic

Bulletin ID: 2026-116-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 09/22/2026 13:00 PM PDT

Description:

s2n-quic is a Rust implementation of the QUIC protocol. We identified CVE-2026-94450, an issue with improper validation of the Destination Connection ID length when a server is configured to send Retry packets. s2n-quic 1.88.0 and earlier allow an unauthenticated user to shut down a server endpoint via a single crafted UDP datagram. No AWS services are affected by this issue, and customers of AWS services do not need to take action. Only server endpoints specifically configured to issue Retry packets are affected.

Impacted versions: <= v1.88.0

Resolution:

This issue has been addressed in s2n-quic version 1.89.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

Workarounds:

There is no workaround that mitigates this issue. Upgrading to the patched version is the recommended remediation.

References:

- CVE-2026-94450
- GHSA-5rw2-6x5m-v22x

 Please email aws-security@amazon.com with any security questions or concerns.

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