CVE-2026-15957
Bulletin ID: 2026-061-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 07/21/2026 12:45 PM 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-2026-15957, where uncontrolled recursion in the JSON, CBOR, and XML deserializer functions emitted by Amazon smithy-rs code generation could allow a third party to cause a denial of service (process abort via stack exhaustion) via a small request containing deeply nested data for a recursive model shape to a generated SDK or server. Impacted versions: aws-sdk-rust crates < release-2026-06-0 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.
CSIRTS triage
- What
- Uncontrolled recursion in deserializer functions can lead to denial of service via stack exhaustion.
- Who is affected
- Deployments using affected versions of smithy-rs for JSON, CBOR, and XML deserialization are at risk.
- Urgency
- Immediate action is required to prevent potential denial of service attacks.
- Action
- Upgrade to the latest version of aws-sdk-rust to mitigate the vulnerability.
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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 (2)
External references
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