CVE-2026-18140Network attack vector

Unauthenticated server crash via recursive JSON skipping

Published Jul 30, 2026 · Updated Jul 30, 2026

Uncontrolled recursion in aws-smithy-json before 0.62.7 allows remote attackers to crash smithy-rs generated servers. The unknown-key skip path recursively descends into deeply nested JSON, and every generated struct deserializer invokes that path without a nesting limit. A single small HTTP request reaches the flaw when an exposed generated server accepts an unknown JSON key, exhausting the process stack and aborting the server.

CVSS severity8.7
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Uncontrolled recursion in aws-smithy-json before 0.62.7 allows remote attackers to crash smithy-rs generated servers. The unknown-key skip path recursively descends into deeply nested JSON, and every generated struct deserializer invokes that path without a nesting limit. A single small HTTP request reaches the flaw when an exposed generated server accepts an unknown JSON key, exhausting the process stack and aborting the server.

The record

CVE
CVE-2026-18140
Published
Jul 30, 2026
Updated
Jul 30, 2026
Vendor
Amazon Web Services
Product
aws-smithy-json
Classifications
CWE-674, CAPEC-230, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.32.0 <=0.62.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Amazon Web Services · aws-smithy-jsonversion=0.32.0 <=0.62.6

Published CVSS scores

7.5Amazon Web ServicesCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7Amazon Web ServicesCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
CAPEC-230Serialized Data with Nested Payloads
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo