CVE-2026-16756
Bulletin ID: 2026-064-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 07/23/2026 11:30 AM PDT Description: Smithy-RS is a Rust code generation and runtime framework that generates HTTP clients and servers from Smithy interface definitions, powering the AWS SDK for Rust and custom service implementations. We identified CVE-2026-16756 where the allocation of resources without limits in the default aws-smithy-http-server serve() path allows unauthenticated "Slowloris" denial of service. Impacted versions: aws-smithy-http-server <= 0.66.4 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.
CSIRTS triage
- What
- The allocation of resources without limits allows unauthenticated Slowloris denial of service.
- Who is affected
- Deployments of aws-smithy-http-server version 0.66.4 and earlier.
- Urgency
- Remediation is important as it allows for denial of service attacks.
- Action
- Update to a version greater than 0.66.4.
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Exploitation outlook
- Low exploitation risk0.42% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 34% of all EPSS-scored CVEs.
Advisory coverage (3)
- highGHSA-jvxp-qmx7-gjpx: Smithy-RS: Allocation of resources without limits in the default aws-smithy-http-server s…ghsa · 2026-07-24
- highCVE-2026-16756: Missing connection and header-read timeouts and the absence of a concurrent-connection cap in …nvd · 2026-07-23
- unknownCVE-2026-16756 - Allocation of resources without limits in the default aws-smithy-http-server serve() path all…aws · 2026-07-23
External references
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[](https://www.csirts.com/cve/CVE-2026-16756)