Live › vulnerability › GHSA-f6f6-6f88-r57j
The AWS Nitro Enclaves SDK for C and its kmstool-enclave example have a use-after-free reachable over vsock from the parent EC2 instance, which can corrupt enclave memory and run code inside the enclave. A second flaw lets a crafted region string make the enclave talk to an impostor KMS and accept forged responses, such as attacker-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 use the aws-nitro-enclaves-sdk-c library at v0.4.5 or earlier. The kmstool-enclave flaw only affects enclave images that include kmstool-enclave or code derived from it; the region-string flaw affects the library itself. Enclaves that do not use this SDK are not affected.
No product ranges from the sources yet.
aws-nitro-enclaves-sdk-c used in your enclave image build.kmstool-enclave or code derived from it.aws-nitro-enclaves-sdk-c v0.4.6, then rebuild enclave images that consume the library.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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