---
id: CVE-2026-15957
title: >-
  Uncontrolled recursion in smithy-rs generated JSON, CBOR, and XML
  deserializers allows unauthenticated remote denial of service via recursive
  shapes
summary: >-
  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.




  Uncontrolled recursion in the JSON,…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-674
vendor: AWS
product: aws-sdk-rust
affected:
  - aws-sdk-rust < release-2026-06-02
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-07-22T18:15:34.870880Z'
published: '2026-07-21'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T18:11:08.949Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-15957'
references:
  - url: 'https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-06-02'
  - url: 'https://aws.amazon.com/security/security-bulletins/2026-061-aws/'
  - url: >-
      https://github.com/smithy-lang/smithy-rs/security/advisories/GHSA-4f2p-7j38-4xrg
tags:
  - cve.org
epss: 0.0075
epssPercentile: 0.54187
ingestedAt: '2026-10-20T19:16:14.558Z'
---

## Overview

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.



Uncontrolled recursion in the JSON, CBOR, and XML deserializer functions emitted by Amazon smithy-rs code generation could allow remote attackers 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.



To mitigate this issue, users should upgrade to aws-sdk-rust release-2026-06-02 or later. Users building custom servers with smithy-rs codegen should regenerate from smithy-rs release-2026-06-01 or later.

## Affected

- `aws-sdk-rust < release-2026-06-02`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.