What is CVE-2026-18140?

CVE-2026-18140 is a high-severity vulnerability in Amazon Aws-Smithy-Json, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-07-30.

How severe is CVE-2026-18140?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Amazon Aws-Smithy-Json

CVE-2026-18140

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.

EPSS: 0.004 (36.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Amazon Aws-smithy-json
Aws Aws-smithy-json — versions 0.32.0

Weakness classification (CWE)

CWE-674 — Uncontrolled Recursion

References

ff89ba41-3aa1-4d27-914a-91399e9639e5 (Product, patch)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (vendor-advisory, Vendor Advisory)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (Vendor Advisory, third-party-advisory)

Frequently asked questions

What is CVE-2026-18140?: CVE-2026-18140 is a high-severity vulnerability in Amazon Aws-Smithy-Json, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-07-30.
How severe is CVE-2026-18140?: High severity. CVSS v3 base score is 7.5 out of 10.