Privasys Go Patch Fixes Critical RA-TLS Certificate Relay Vulnerability

Privasys has released a security update for its Go programming language fork to address a critical vulnerability that could allow attackers to spoof trusted enclave connections. The flaw, identified as CVE-2026-108267, affects versions prior to privasys-v0.5.1-go1.26.5 and has been rated Critical with a CVSS score of 9.1 by the National Vulnerability Database.

The vulnerability stems from how the library handles Remote Attestation TLS (RA-TLS) certificates in challenge mode. According to the NVD record, earlier versions bound the quote ReportData to the certificate’s public key and a client nonce, but failed to bind it to the active TLS session. This missing binding allows an attacker who has obtained an enclave TLS private key to take a genuine attestation quote and relay it onto a different connection. Consequently, a relying party may accept a handshake terminated by the attacker as if it were a legitimate, attested enclave connection.

Technical Context and Background

Privasys Go is described as a maintained fork of the standard Go programming language. Its primary distinction is the addition of RA-TLS support to the `crypto/tls` package, facilitating secure remote attestation for software running in trusted execution environments. The specific weakness is categorized under CWE-346, which relates to insufficient verification of data authenticity.

In a typical RA-TLS handshake, the relying party verifies that the code running on the remote system is genuine and untampered. The flaw in the affected versions of Privasys Go created a gap in this verification process. Because the attestation data was not cryptographically tied to the specific TLS session in which it was presented, an adversary could capture a valid quote from one session and reuse it in another. This relay attack undermines the integrity guarantees that RA-TLS is designed to provide, potentially allowing unauthorized actors to impersonate trusted enclaves.

Who Is Affected

The vulnerability affects any system or application using the Privasys Go library with a version number lower than privasys-v0.5.1-go1.26.5. Organizations relying on this specific fork for implementing remote attestation in their Go-based applications are exposed to the risk of certificate relay attacks.

The impact is significant for environments that depend on the authenticity of enclave connections for security-critical operations. If an attacker can successfully relay a certificate, they can bypass the attestation checks intended to verify the remote party's identity and code integrity. This could lead to unauthorized access or the execution of malicious code under the guise of a trusted enclave.

What should you do?

Users of Privasys Go should verify their current library version immediately. If the version is older than privasys-v0.5.1-go1.26.5, they should upgrade to the patched release to mitigate the relay vulnerability. The vendor has confirmed that the issue is fixed in the latest release.