CVE-2021-45696 Explained : Impact and Mitigation

An issue was discovered in the sha2 crate 0.9.7 before 0.9.8 for Rust. Hashes of long messages may be incorrect when the AVX2-accelerated backend is used.

Understanding CVE-2021-45696

This CVE identifies a vulnerability in the sha2 crate for Rust that could lead to incorrect hashes of long messages when utilizing the AVX2-accelerated backend.

What is CVE-2021-45696?

The CVE-2021-45696 vulnerability pertains to the sha2 crate versions 0.9.7 through 0.9.8 in Rust, potentially resulting in inaccurate hash calculations for extended messages under specific conditions.

The Impact of CVE-2021-45696

The vulnerability could compromise the integrity and accuracy of hashed data, impacting systems reliant on the affected versions of the sha2 crate with the AVX2-accelerated backend.

Technical Details of CVE-2021-45696

This section outlines the technical aspects of the CVE.

Vulnerability Description

The issue occurs in the sha2 crate versions 0.9.7 to 0.9.8 for Rust, leading to miscalculations in the hashes of lengthy messages when the AVX2-accelerated backend is active.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions: 0.9.7 through 0.9.8

Exploitation Mechanism

The vulnerability arises from the incorrect processing of hash values during message hashing with the AVX2-accelerated backend in the sha2 crate for Rust.

Mitigation and Prevention

Protect your systems against CVE-2021-45696 using the following strategies.

Immediate Steps to Take

Update to sha2 crate version 0.9.8 or a secure release that addresses the vulnerability.
Disable the AVX2-accelerated backend if possible to mitigate the issue.

Long-Term Security Practices

Regularly monitor and apply updates to dependencies to prevent potential vulnerabilities.
Implement secure coding practices to minimize the risk of hash calculation errors.

Patching and Updates

Stay informed about security advisories and promptly apply patches to address known vulnerabilities.