CVE-2026-119148 in aws-nitro-enclaves-sdk-c
Summary
by MITRE • 10/30/2026
Incomplete string validation in AWS aws-nitro-enclaves-sdk-c before 0.4.6 may allow a third party to impersonate the AWS KMS endpoint.
To remediate this issue, users should rebuild any custom enclave image against aws-nitro-enclaves-sdk-c 0.4.6.
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Analysis
by VulDB Data Team • 10/30/2026
The vulnerability identified in versions of the AWS Nitro Enclaves SDK for C prior to version 0.4.6 stems from an incomplete string validation mechanism within the library's communication logic with the Key Management Service endpoint. This flaw allows a malicious actor, particularly one who has gained access to the network traffic or can manipulate the local enclave environment, to perform a man-in-the-middle attack by impersonating the legitimate AWS KMS service. The root cause lies in the SDK failing to rigorously validate the identity of the remote endpoint during the TLS handshake or subsequent API calls, relying instead on potentially insufficient checks that do not fully verify certificate chains or hostname consistency against expected trusted authorities specific to the Nitro Enclave environment.
From a technical perspective, this deficiency represents a classic failure in cryptographic binding and service authentication. When an enclave attempts to retrieve encryption keys or perform cryptographic operations via KMS, it must ensure it is communicating with the genuine AWS infrastructure rather than a spoofed endpoint controlled by an attacker. The incomplete validation means that if an adversary can intercept the connection or redirect DNS queries within the isolated network boundary of the Nitro Enclave, they can present a fraudulent certificate. Because the SDK does not strictly enforce strict hostname verification and full chain-of-trust validation against the specific AWS KMS endpoints, it accepts this malicious identity as legitimate. This aligns with CWE-295 Improper Certificate Validation and CWE-347 Improper Verification of Cryptographic Signature, highlighting a critical lapse in ensuring that cryptographic operations are bound to the correct service entity.
The operational impact of this vulnerability is severe for any workload running within Nitro Enclaves that relies on AWS KMS for key management or encryption services. If an attacker successfully impersonates the KMS endpoint, they can intercept sensitive data being encrypted or decrypted by the enclave. This could lead to the exfiltration of plaintext secrets, manipulation of cryptographic outputs, or complete compromise of the confidentiality and integrity guarantees provided by the enclaves. Since Nitro Enclaves are designed for high-security workloads where even cloud providers cannot access the memory contents, bypassing these controls undermines the fundamental security model of the platform. The attacker could potentially decrypt sensitive data stored within the enclave's protected memory or inject malicious keys into the application logic, leading to broader system compromise and potential regulatory violations regarding data protection standards such as GDPR or HIPAA if personal health information is involved.
To mitigate this risk, organizations must immediately update their build pipelines to compile custom enclave images against aws-nitro-enclaves-sdk-c version 0.4.6 or later. This updated release includes the necessary patches that enforce strict validation of the KMS endpoint identity, ensuring that only certificates issued by trusted AWS authorities are accepted. Additionally, security teams should review their CI/CD processes to ensure that dependencies are regularly audited and kept up-to-date with vendor-recommended versions. Implementing network-level monitoring within the enclave environment can also help detect anomalous connection attempts or certificate anomalies, providing an additional layer of defense-in-depth against potential exploitation attempts targeting this specific weakness in older SDK implementations.