How severe is CVE-2026-18140?

CVE-2026-18140 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-18140 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-18140?

CVE-2026-18140 affects Amazon Aws-smithy-json. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-18140?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-18140 published?

CVE-2026-18140 was published on 2026-07-30 and last updated on 2026-08-10.

CVE-2026-18140

CVE-2026-18140 is a high-severity vulnerability in Amazon Aws-smithy-json with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-674.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
EPSS exploit prediction: 0% (37th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-674
Affected product: Amazon Aws-smithy-json
Published: 2026-07-30
Last modified: 2026-08-10

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-18140?: CVE-2026-18140 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-18140 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-18140?: CVE-2026-18140 affects Amazon Aws-smithy-json. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-18140?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-18140 published?: CVE-2026-18140 was published on 2026-07-30 and last updated on 2026-08-10.

References

Affected products (1)

cpe:2.3:a:amazon:aws-smithy-json:*:*:*:*:*:rust:*:*

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