CVE-2026-108268 in Enclave OS Virtual
Summary
by MITRE • 10/10/2026
Enclave OS Virtual runs container workloads inside confidential virtual machines with end-to-end attestation. Prior to tdx-v0.2.43 and tdx-gpu-v0.6.27, the TDX/GPU RA-TLS certificate issuer placed the certificate public-key hash and client nonce in quote ReportData but omitted a value bound to the active TLS session. An attacker who obtained an enclave TLS private key could relay a genuine quote onto another connection, causing a relying party to accept an attacker-terminated connection as the attested enclave. This issue is fixed in tdx-v0.2.43 and tdx-gpu-v0.6.27.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/10/2026
The vulnerability identified in Enclave OS Virtual prior to versions tdx-v0.2.43 and tdx-gpu-v0.6.27 represents a critical flaw in the Remote Attestation Transport Layer Security implementation for confidential virtual machines. This system is designed to run container workloads within hardware-isolated environments, relying on end-to-end attestation to verify that the software running inside the enclave has not been tampered with and originates from a trusted source. The core technical failure lies in how the TDX or GPU RA-TLS certificate issuer constructs the quote's ReportData field. Specifically, while the implementation correctly includes the public-key hash of the certificate and a client nonce to prevent replay attacks within a single session context, it fails to bind these values to the specific active TLS session parameters. This omission creates a gap in cryptographic binding that undermines the integrity of the authentication process.
From an operational perspective, this flaw enables a sophisticated man-in-the-middle attack scenario known as quote relaying or certificate pinning bypass through session hijacking techniques. An attacker who has compromised the enclave's TLS private key can intercept legitimate attestation quotes generated by the trusted environment. Because the quote lacks binding to the specific TLS session context, such as unique ephemeral keys or session identifiers that change per connection, the attacker can capture a valid quote from one established secure channel and inject it into a different, maliciously controlled connection. The relying party, which is responsible for verifying the attestation evidence, will validate the cryptographic signatures within the quote successfully since they are genuine. However, because the verification process does not confirm that this specific quote was generated in response to the current session's unique parameters, the relying party incorrectly accepts the attacker-terminated connection as a legitimate, attested enclave instance.
This vulnerability fundamentally breaks the trust model of confidential computing by allowing an adversary to impersonate a trusted service without needing to break the underlying hardware isolation or cryptographic algorithms directly. The impact is severe in enterprise environments where sensitive data processing occurs within these enclaves, such as financial transactions, healthcare records analysis, or intellectual property protection. An attacker could potentially exfiltrate sensitive data processed by the enclave or inject malicious payloads into the workload while maintaining the appearance of a secure, verified connection to downstream services and clients. This undermines the primary value proposition of confidential computing, which is ensuring that code and data remain protected even from privileged infrastructure operators like cloud providers.
The issue aligns with CWE-295 Improper Certificate Validation, as the system fails to properly validate the binding between the certificate evidence and the current session context. It also relates to ATT&CK technique T1078 Valid Accounts or more specifically aspects of lateral movement and credential access where valid credentials are misused in unauthorized contexts. The root cause is a design flaw in the cryptographic protocol implementation rather than a simple coding error, highlighting the complexity of integrating hardware-based attestation with standard TLS workflows.
To mitigate this vulnerability, organizations must immediately update their Enclave OS Virtual environments to version tdx-v0.2.43 or later for CPU-based TDX workloads and tdx-gpu-v0.6.27 or later for GPU-accelerated workloads. These updated versions correct the ReportData construction logic by ensuring that session-specific parameters are included in the attestation quote, thereby cryptographically binding each certificate issuance to its specific TLS session. This prevents an attacker from reusing a valid quote across different connections. Additionally, security teams should review their deployment configurations to ensure no legacy instances remain unpatched and consider implementing additional network-level controls such as mutual TLS with strict client certificate validation that includes session-specific challenges beyond standard RA-TLS mechanisms where applicable. Regular auditing of attestation logs can also help detect anomalies indicative of quote relaying attempts, although the primary defense remains timely patching to address this fundamental protocol deficiency.