CVE-2026-94450 Potential denial of service when configured to send Retry packets in s2n-quic
An unauthenticated remote attacker can cause a denial of service in s2n-quic servers configured to send Retry packets by sending a crafted UDP datagram.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-94450?
CVE-2026-94450 is a high-severity denial of service vulnerability in AWS s2n-quic, published on 22 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Improper validation of the Destination Connection ID length in s2n-quic 1.88.0 and earlier may allow an unauthenticated remote user to cause a denial of service by shutting down a server endpoint via a single crafted UDP datagram. Only server endpoints specifically configured to send Retry packets are affected.
To remediate this issue, users should upgrade to version v1.89.0 or later.
Which versions are affected by CVE-2026-94450?
How do I fix CVE-2026-94450?
No fix has been published for CVE-2026-94450 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-94450 being exploited?
There is no known exploitation of CVE-2026-94450 in the wild and no public exploit code.
Sources
Also known as GHSA-5rw2-6x5m-v22x.