Uncontrolled recursion in the aws-smithy-json unknown-key skip path allows unauthenticated remote denial of service in smithy-rs generated servers
Summary
| CVE | CVE-2026-18140 |
|---|---|
| State | PUBLISHED |
| Assigner | AMZN |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-30 19:17:26 UTC |
| Updated | 2026-08-10 20:04:05 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 8.7 HIGH from ff89ba41-3aa1-4d27-914a-91399e9639e5
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.004360000 probability, percentile 0.360170000 (date 2026-08-11)
Problem Types: CWE-674 | CWE-674 CWE-674: Uncontrolled Recursion
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | ff89ba41-3aa1-4d27-914a-91399e9639e5 | Secondary | 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/E:X/C... |
| 4.0 | CNA | CVSS | 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 |
| 3.1 | ff89ba41-3aa1-4d27-914a-91399e9639e5 | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
NoneConfidentiality
NoneIntegrity
NoneAvailability
HighSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Amazon | Aws-smithy-json | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | AWS | Aws-smithy-json | affected 0.32.0 0.62.6 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/smithy-lang/smithy-rs/security/advisories/GHSA-8ffr-xgwf-xj56 | ff89ba41-3aa1-4d27-914a-91399e9639e5 | github.com | Vendor Advisory |
| aws.amazon.com/security/security-bulletins/2026-067-aws | ff89ba41-3aa1-4d27-914a-91399e9639e5 | aws.amazon.com | Vendor Advisory |
| crates.io/crates/aws-smithy-json/0.62.7 | ff89ba41-3aa1-4d27-914a-91399e9639e5 | crates.io | Product |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.