CVE-2025-59693 identifies a hardware security vulnerability in Entrust nShield Connect XC, nShield 5c, and nShield HSMi devices up to versions 13.6.11 and 13.7. These HSMs are designed to securely generate, store, and manage cryptographic keys and perform cryptographic operations in a tamper-resistant environment. The vulnerability arises from the Chassis Management Board, which allows a physically proximate attacker to bypass the tamper-evident label protecting the device chassis. By doing so, the attacker can open the chassis without triggering tamper alerts or leaving evidence of intrusion. Once inside, the attacker can access the JTAG (Joint Test Action Group) connector, a hardware debugging interface typically used for development and troubleshooting. Access to JTAG enables the attacker to gain debug access, escalate privileges, and potentially extract sensitive cryptographic material or manipulate the HSM's firmware and operations. This attack requires physical proximity but no specialized authentication or user interaction. The vulnerability undermines the fundamental security guarantees of the HSM, threatening confidentiality and integrity of cryptographic keys and operations. No public exploits have been reported yet, but the risk is significant given the critical role of these devices in securing sensitive data and infrastructure.

For European organizations, this vulnerability poses a critical risk to the security of cryptographic keys and operations protected by Entrust nShield HSMs. These devices are widely used in sectors such as banking, government, telecommunications, and critical infrastructure to secure digital identities, financial transactions, and sensitive communications. Exploitation could lead to unauthorized key extraction, enabling attackers to decrypt confidential data, forge digital signatures, or impersonate trusted entities. The stealthy nature of the attack—bypassing tamper evidence—complicates incident detection and response. This could result in prolonged undetected compromises, undermining trust in cryptographic protections and compliance with regulations such as GDPR and NIS Directive. Additionally, the ability to escalate privileges and manipulate HSM firmware could facilitate further attacks on connected systems. The physical access requirement limits the attack surface but does not eliminate risk, especially in environments with shared or insufficiently secured hardware rooms or data centers.

1. Enhance physical security controls around Entrust nShield HSMs, including restricted access to hardware rooms, surveillance, and security personnel. 2. Implement multi-factor authentication and strict access policies for all personnel with physical access to HSMs. 3. Regularly inspect HSM chassis and tamper-evident seals for signs of unauthorized access, and consider using more robust tamper-evident technologies resistant to bypass. 4. Coordinate with Entrust to obtain firmware updates or patches that may address or mitigate this vulnerability once available. 5. Employ hardware security monitoring tools that can detect anomalous debug or JTAG activity. 6. Segregate HSMs in secure enclosures or locked cabinets with additional tamper detection sensors. 7. Conduct regular security audits and penetration tests focusing on physical security controls. 8. Develop incident response plans specifically addressing physical tampering scenarios. 9. Limit the number of personnel with physical access and enforce strict logging of all access events. 10. Consider alternative HSM solutions with stronger physical tamper protections if risk cannot be adequately mitigated.