---
id: "CVE-2026-119148"
kind: "vulnerability"
aliases: ["CVE-2026-119148"]
title: "Incomplete string validation in AWS aws-nitro-enclaves-sdk-c before 0.4.6 may allow a third party to impersonate the\u2026"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["aws", "c", "infrastructure", "kms", "lab-disclosure", "nitro-enclaves", "self-hosted"]
not_affected_if: ["no-kmstool-enclave", "no-nitro-enclaves"]
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-2026-119148", "first_seen_at": "2026-10-30T17:31:39+00:00"}]
---

# Incomplete string validation in AWS aws-nitro-enclaves-sdk-c before 0.4.6 may allow a third party to impersonate the…

The AWS Nitro Enclaves SDK for C has two issues: a use-after-free in the kmstool-enclave example's SetClient handler that lets a process on the parent EC2 instance run code inside the enclave, and a KMS server name built from a caller-supplied region that lets a third party impersonate KMS and inject forged responses such as attacker-chosen key material. Both are fixed in v0.4.6.

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

## How to check

- Check the aws-nitro-enclaves-sdk-c version your enclave images build against; versions `<= v0.4.5` are affected.
- Check whether your enclave images include kmstool-enclave or code derived from it; only those are affected by CVE-2026-119116.

## Fix

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

## 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-2026-119148

## 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_