What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-21 · updated 2026-10-24
• Weakness: CWE-674

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. 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 products

• aws-sdk-rust: before release-2026-06-02 — fixed in release-2026-06-02

How to fix

Upgrade to a fixed version: aws-sdk-rust release-2026-06-02. Check the vendor advisory for mitigations.

References

• https://aws.amazon.com/security/security-bulletins/2026-061-aws/
• https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-06-02
• https://github.com/smithy-lang/smithy-rs/security/advisories/GHSA-4f2p-7j38-4xrg

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