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

State: Published
Severity: 8.7 High
Published: Jul 30, 2026
Updated: Jul 30, 2026
Reserved: Jul 28, 2026

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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.

Scores

CVSS	Score	Vector	Source
4.0	8.7 High	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	AMZN
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	AMZN

Weaknesses

CWE-674 Uncontrolled Recursion

Affected Products

Product	Versions
aws-smithy-jsonAWS	0.32.0 through 0.62.6Affected

References

https://crates.io/crates/aws-smithy-json/0.62.7patch
https://aws.amazon.com/security/security-bulletins/2026-067-aws/vendor-advisory
https://github.com/smithy-lang/smithy-rs/security/advisories/GHSA-8ffr-xgwf-xj56third-party-advisory

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