What’s Vulnerable › Vulnerabilities

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

• 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: 2026-07-30 · updated 2026-10-23
• Weakness: 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 products

• aws-smithy-json: before 0.62.7 — fixed in 0.62.7

How to fix

Upgrade to a fixed version: aws-smithy-json 0.62.7. Check the vendor advisory for mitigations.

References

• https://aws.amazon.com/security/security-bulletins/2026-067-aws/
• https://crates.io/crates/aws-smithy-json/0.62.7
• https://github.com/smithy-lang/smithy-rs/security/advisories/GHSA-8ffr-xgwf-xj56

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