CVE-2026-119116 and CVE-2026-119148 - Issues in AWS Nitro Enclaves SDK for C
Bulletin ID: 2026-157-AWS
Scope: AWS
Content Type: Important (requires attention)
Publication Date: 10/30/2026 09:00 AM PDT
Description:
The AWS Nitro Enclaves SDK for C (aws-nitro-enclaves-sdk-c) is a library and set of example tools, including kmstool-enclave, for building applications that run inside AWS Nitro Enclaves and call AWS KMS using cryptographic attestation.
We identified CVE-2026-119116, a use-after-free in the SetClient command handler of the kmstool-enclave example application, where an application that executes on the parent EC2 instance could send crafted messages over vsock to corrupt heap memory inside the enclave and execute arbitrary code within it. Only enclave images that include kmstool-enclave, or code derived from it, are affected.
We also identified CVE-2026-119148, an input validation issue in the SDK library where the AWS KMS server name is built from a caller-supplied region string. A third party could supply a crafted region to impersonate KMS to the enclave and inject forged responses, such as actor-chosen key material.
Impacted versions: aws-nitro-enclaves-sdk-c <= v0.4.5 (CVE-2026-119116 affects kmstool-enclave only; CVE-2026-119148 affects the library)
Resolution:
Both issues have been addressed in aws-nitro-enclaves-sdk-c version v0.4.6. Customers who build enclave images which consume the aws-nitro-enclaves-sdk-c library should upgrade it to v0.4.6 and rebuild their enclave images.
Workarounds:
There are no workarounds. Upgrading is required.
References:
Acknowledgement:
We would like to thank Trail of Bits for reporting CVE-2026-119116 and collaborating on this issue through the coordinated vulnerability disclosure process.
Please email aws-security@amazon.com with any security questions or concerns.