CVE-2021-45451 Explained : Impact and Mitigation

In Mbed TLS before 3.1.0, psa_aead_generate_nonce allows policy bypass or oracle-based decryption when the output buffer is at memory locations accessible to an untrusted application.

Understanding CVE-2021-45451

What is CVE-2021-45451?

CVE-2021-45451 is a vulnerability in Mbed TLS before version 3.1.0 that allows a policy bypass or oracle-based decryption under specific conditions.

The Impact of CVE-2021-45451

This vulnerability can lead to security breaches, enabling unauthorized access to encrypted data by bypassing security policies or employing decryption through an oracle.

Technical Details of CVE-2021-45451

Vulnerability Description

The vulnerability exists in the psa_aead_generate_nonce function in Mbed TLS, specifically before version 3.1.0, affecting the nonce generation process.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Versions Affected: All versions before Mbed TLS 3.1.0

Exploitation Mechanism

The vulnerability can be exploited when the output buffer is located in memory accessible to an untrusted application, allowing for policy bypass or oracle-based decryption.

Mitigation and Prevention

Immediate Steps to Take

Update to Mbed TLS version 3.1.0 or later to mitigate this vulnerability.
Restrict memory access permissions to prevent untrusted applications from accessing critical memory locations.

Long-Term Security Practices

Implement strict input validation to avoid buffer overflows and memory-related vulnerabilities.
Regularly monitor and audit memory access patterns for any suspicious activities.

Patching and Updates

Apply security patches promptly and consistently to address known vulnerabilities in Mbed TLS and other software components.