# CVE-2026-18140: Uncontrolled recursion in the aws-smithy-json unknown-key skip path allows unauthenticated remote denial of service in smithy-rs generated servers

> CVE-2026-18140: Uncontrolled recursion in the aws-smithy-json unknown-key skip path allows unauthenticated remote denial of service in smithy-rs generated servers. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-18140
Last updated: 2026-10-23T22:10:00Z

- Published: 2026-07-30 18:34 UTC · Updated: 2026-10-23 22:10 UTC · Assigner: AMZN
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.78%, 56th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-674

## Description

Uncontrolled recursion in the unknown-key skip path of the aws-smithy-json runtime crate before 0.62.7, which the smithy-rs code generator invokes from every generated struct deserializer, might allow remote unauthenticated users to cause a denial of service (process abort via stack exhaustion) via a single small HTTP request containing deeply nested JSON to a smithy-rs generated server. To remediate this issue, users should upgrade to aws-smithy-json 0.62.7 or later and rebuild.

## Affected vendors and products

- AWS: aws-smithy-json

## Tracked companies

- [Amazon Web Services](https://rewindex.com/company/aws.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-18140)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-18140)
- [https://aws.amazon.com/security/security-bulletins/2026-067-aws/](https://aws.amazon.com/security/security-bulletins/2026-067-aws/)
- [https://crates.io/crates/aws-smithy-json/0.62.7](https://crates.io/crates/aws-smithy-json/0.62.7)
- [https://github.com/smithy-lang/smithy-rs/security/advisories/GHSA-8ffr-xgwf-xj56](https://github.com/smithy-lang/smithy-rs/security/advisories/GHSA-8ffr-xgwf-xj56)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-18140 · Markdown: https://rewindex.com/cve/CVE-2026-18140.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-18140 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:35.853Z