CVE-2026-16756 - Allocation of resources without limits in the default aws-smithy-http-server serve() path allows unauthenticated Slowloris denial of service
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.
AI Analysis
Technical Summary
The vulnerability CVE-2026-16756 affects aws-smithy-http-server, a Rust framework used for generating HTTP clients and servers. The default serve() path allocates resources without imposing limits, which allows unauthenticated attackers to exploit a Slowloris denial of service attack by holding connections open and exhausting server resources. This can disrupt service availability. The issue impacts all versions up to and including 0.66.4. AWS has addressed this vulnerability in version 0.66.5, and users are advised to upgrade to this or later versions to mitigate the risk.
Potential Impact
An unauthenticated attacker can cause a denial of service by exploiting unlimited resource allocation in the server's serve() path, leading to service disruption. This affects availability but does not indicate compromise of data confidentiality or integrity.
Mitigation Recommendations
Upgrade aws-smithy-http-server to version 0.66.5 or later. There are no workarounds other than applying the official patch. Ensure any forked or derivative code is also updated to incorporate the fix.
CVE-2026-16756 - Allocation of resources without limits in the default aws-smithy-http-server serve() path allows unauthenticated Slowloris denial of service
Description
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.
Affected software
pkg:cargo/aws-smithy-http-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-16756 affects aws-smithy-http-server, a Rust framework used for generating HTTP clients and servers. The default serve() path allocates resources without imposing limits, which allows unauthenticated attackers to exploit a Slowloris denial of service attack by holding connections open and exhausting server resources. This can disrupt service availability. The issue impacts all versions up to and including 0.66.4. AWS has addressed this vulnerability in version 0.66.5, and users are advised to upgrade to this or later versions to mitigate the risk.
Potential Impact
An unauthenticated attacker can cause a denial of service by exploiting unlimited resource allocation in the server's serve() path, leading to service disruption. This affects availability but does not indicate compromise of data confidentiality or integrity.
Mitigation Recommendations
Upgrade aws-smithy-http-server to version 0.66.5 or later. There are no workarounds other than applying the official patch. Ensure any forked or derivative code is also updated to incorporate the fix.
Technical Details
- Article Source
- {"url":"https://aws.amazon.com/security/security-bulletins/rss/2026-064-aws/","fetched":true,"fetchedAt":"2026-07-23T18:47:37.780Z","wordCount":171}
- Classification
- {"confidence":0.88,"severitySource":"heuristic","classifier":"rss-v2"}
Threat ID: 6a6261c99c2644c7f888dc65
Added to database: 07/23/2026, 18:47:37 UTC
Last enriched: 08/15/2026, 18:31:38 UTC
Last updated: 09/05/2026, 10:52:07 UTC
Views: 161
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.