AmazonAnalysisAWS Nitro Enclaves SDK fixes use-after-free and KMS spoofing flaws
What happened.Amazon Web Services published security bulletin 2026-157-AWS detailing memory corruption and service impersonation vulnerabilities in the AWS Nitro Enclaves SDK for C.
Why it matters.Confidential computing enclaves protect high-value cryptographic keys and proprietary algorithms from compromised host operating systems. When socket messages corrupt enclave memory and input defects permit KMS response spoofing, host-level attackers breach confidential computing guarantees. Infrastructure engineers running Nitro enclaves must rebuild enclave binaries with SDK v0.4.6. Security teams should audit attestation configurations to verify enclave image integrity.
The technical specifications:
- Vulnerability mechanics: Tracked as CVE-2026-119116, a use-after-free defect in the kmstool-enclave example permits code execution inside enclaves via crafted vsock messages.
- Service spoofing: Tracked as CVE-2026-119148, an input validation flaw allows third parties to supply crafted region strings, impersonating AWS KMS to the enclave.
- Security boundary impact: The flaws weaken isolation boundaries between parent EC2 host instances and confidential computing enclaves processing cryptographic material.
- Affected packages: Both vulnerabilities affect the aws-nitro-enclaves-sdk-c library across versions preceding v0.4.6.
- Remediation release: AWS released SDK version v0.4.6, instructing engineering teams to rebuild and redeploy all enclave images using the updated C library.