CVE-2026-16756 Smithy-RS: Allocation of resources without limits in the default aws-smithy-http-server serve() path allows unauthenticated Slowloris denial of service
Remote attackers can cause denial of service by exhausting server resources via Slowloris attacks due to missing timeouts and connection limits in the default configuration.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-16756?
CVE-2026-16756 is a high-severity denial of service vulnerability in aws-smithy-http-server, published on 23 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Missing connection and header-read timeouts and the absence of a concurrent-connection cap in the default serve() path of Amazon aws-smithy-http-server might allow remote attackers to cause a denial of service by opening many connections and sending partial requests that are never completed, exhausting server sockets and tasks.
To mitigate this issue, users should upgrade to aws-smithy-http-server 0.66.5 or later.
Weakness: CWE-770
Which versions are affected by CVE-2026-16756?
2 open source packages ship an affected version, including aws-smithy-http-server.
| Package | Affected | Fixed in |
|---|---|---|
aws-smithy-http-server crates.io | All versions | 0.66.5 |
aws-smithy-http-server crates.io | All versions | 0.66.5 |
How do I fix CVE-2026-16756?
Upgrade aws-smithy-http-server to 0.66.5 or later.
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-2026-16756 being exploited?
There is no known exploitation of CVE-2026-16756 in the wild and no public exploit code.
Sources
Also known as GHSA-jvxp-qmx7-gjpx.