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Vulnerability record · CVE-2026-15957 · published 21 July 2026

CVE-2026-15957: Allocation without limits vulnerability

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.

8.7 CVSS 4.0 High EPSS 0.75% · top 46.9% CWE-770 · Allocation without limits Awaiting Analysis
8.7CVSS 4.0 base score
0.75%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
22 Jul 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
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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Source: NIST National Vulnerability Database (record CVE-2026-15957), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.