CVE-2021-46922 is a vulnerability identified in the Linux kernel's Trusted Platform Module (TPM) integration, specifically within the KEYS subsystem responsible for trusted key management. The issue arises from a regression introduced during a patch rebase, where the function call tpm_try_get_ops() was inadvertently removed from the tpm2_seal_trusted() function. This omission leads to an imbalance in TPM operation references, causing improper handling of TPM operations. The consequence is kernel oops (crashes) on hardware that uses the TPM Interface Specification (TIS) for TPM communication. TPM is a hardware-based security module used for cryptographic operations such as sealing and unsealing keys, which are critical for system integrity and secure boot processes. The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is present in certain development or stable branches prior to the fix. Although no known exploits are reported in the wild, the flaw can cause system instability or denial of service due to kernel crashes when TPM seal/unseal operations are invoked. The fix restores the missing tpm_try_get_ops() call, ensuring proper TPM operation reference counting and preventing the kernel oops on affected hardware.

For European organizations relying on Linux systems with TPM hardware, this vulnerability could lead to unexpected kernel crashes during TPM seal/unseal operations. This can disrupt services that depend on hardware-based security features such as disk encryption, secure boot, or trusted key storage, potentially causing denial of service conditions. Organizations using TPM-enabled Linux servers, workstations, or embedded devices may experience system instability or downtime, impacting business continuity and security posture. Although the vulnerability does not directly expose sensitive data or allow privilege escalation, the resulting kernel oops can degrade system availability and reliability. In sectors like finance, healthcare, or critical infrastructure within Europe, where TPM is often used to enforce strong security policies, this instability could hinder compliance and operational security. However, since exploitation requires specific TPM hardware and invoking seal/unseal operations, the attack surface is somewhat limited. No evidence of active exploitation reduces immediate risk but patching remains important to maintain system stability and trust in TPM-based security mechanisms.

European organizations should promptly apply the Linux kernel patch that restores the tpm_try_get_ops() call in the tpm2_seal_trusted() function. Specifically, updating to a Linux kernel version that includes the fix for CVE-2021-46922 is essential. Organizations should audit their Linux systems to identify those running affected kernel versions and verify the presence of TPM hardware using the TIS interface. For critical systems, testing the updated kernel in a staging environment before deployment is advisable to ensure compatibility and stability. Additionally, monitoring kernel logs for TPM-related oops or crashes can help detect if the vulnerability is being triggered. Organizations should also review their TPM usage policies and ensure that applications invoking TPM seal/unseal operations handle errors gracefully to avoid cascading failures. Maintaining up-to-date firmware for TPM modules and ensuring secure configuration of TPM features will further reduce risk. Finally, incorporating this vulnerability into vulnerability management and patching workflows will help prevent future regressions.