---
id: "CVE-2026-119116"
kind: "vulnerability"
aliases: ["CVE-2026-119116"]
title: "A use-after-free and double-free issue in the SetClient command handler of the kmstool-enclave sample application of\u2026"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["aws", "c", "enclave-images", "kms", "lab-disclosure", "nitro-enclaves", "package"]
not_affected_if: ["no-nitro-enclaves", "not-using-kmstool-enclave"]
published_at: "2026-10-30T00:00:00+00:00"
first_seen_at: "2026-10-30T16:50:06+00:00"
updated_at: "2026-10-30T17:31:39+00:00"
sources: [{"source": "lab", "url": "https://aws.amazon.com/security/security-bulletins/rss/2026-157-aws/", "first_seen_at": "2026-10-30T16:50:06+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119116", "first_seen_at": "2026-10-30T17:31:39+00:00"}]
---

# A use-after-free and double-free issue in the SetClient command handler of the kmstool-enclave sample application of…

The AWS Nitro Enclaves SDK for C and its example tool kmstool-enclave contain a use-after-free reachable from the parent EC2 instance over vsock, and a region-to-server-name flaw that lets a third party impersonate KMS to the enclave. An attacker can run code inside an affected enclave or inject forged KMS responses such as attacker-chosen key material.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the version of aws-nitro-enclaves-sdk-c your enclave images build against; affected versions are `<= v0.4.5`.
- Check whether enclave images include kmstool-enclave or code derived from it.
- Check whether the SDK library is used to call KMS from inside the enclave.

## Fix

- aws-nitro-enclaves-sdk-c: upgrade to `v0.4.6` and rebuild enclave images

## Timeline

- 2026-10-30T16:50:06+00:00 lab https://aws.amazon.com/security/security-bulletins/rss/2026-157-aws/ — AWS: CVE-2026-119116 and CVE-2026-119148 - Issues in AWS Nitro Enclaves SDK for C
- 2026-10-30T17:31:39+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119116

## Documents

- [advisory] AWS: CVE-2026-119116 and CVE-2026-119148 - Issues in AWS Nitro Enclaves SDK for C https://aws.amazon.com/security/security-bulletins/rss/2026-157-aws/

## From the sources

CVE-2026-119116 and CVE-2026-119148 - Issues in AWS Nitro Enclaves SDK for C

### 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:

- CVE-2026-119116
- CVE-2026-119148
- GHSA-f6f6-6f88-r57j
- GHSA-cfhm-qfw4-j7qq

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_