Live › vulnerability › GHSA-cfhm-qfw4-j7qq
The AWS Nitro Enclaves SDK for C has two issues: a use-after-free in the kmstool-enclave example lets a process on the parent EC2 instance send crafted vsock messages to run code inside the enclave, and a region string used to build the KMS server name lets a third party impersonate KMS and inject forged responses, including chosen key material.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-30 16:50 UTC. All times on this page are UTC.
Teams building applications that run inside AWS Nitro Enclaves and call AWS KMS through the aws-nitro-enclaves-sdk-c library or its kmstool-enclave example. The vsock flaw matters only for enclave images that include kmstool-enclave or code derived from it; the region-based KMS impersonation flaw affects the library itself. Teams not using Nitro Enclaves with this SDK can skip it.
No product ranges from the sources yet.
aws-nitro-enclaves-sdk-c your enclave images build against; versions <= v0.4.5 are affected.kmstool-enclave or code derived from it; only those images are affected for CVE-2026-119116.aws-nitro-enclaves-sdk-c v0.4.6; rebuild enclave images after upgrading.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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 [email protected] with any security questions or concerns.
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