CVE-2021-28878 : Security Advisory and Response

In April 2021, a vulnerability known as CVE-2021-28878 was identified in the standard library of Rust before version 1.52.0. The issue stemmed from the Zip implementation making multiple calls to __iterator_get_unchecked() for the same index, potentially leading to a memory safety violation. This article delves into the details of CVE-2021-28878 and provides insights into its impact, technical details, and mitigation strategies.

Understanding CVE-2021-28878

CVE-2021-28878 is a security flaw found in Rust's standard library prior to version 1.52.0. The vulnerability arises due to the Zip implementation making repeated calls to __iterator_get_unchecked(), which could result in a memory safety violation.

What is CVE-2021-28878?

The vulnerability in CVE-2021-28878 is attributed to the Zip implementation in Rust, specifically when next_back() and next() functions are used concurrently. This behavior violates a safety requirement for the TrustedRandomAccess trait, potentially compromising memory safety.

The Impact of CVE-2021-28878

CVE-2021-28878 could lead to a memory safety violation, opening the door to potential exploitation by malicious actors. By exploiting this vulnerability, attackers could compromise the integrity and security of systems running affected versions of Rust.

Technical Details of CVE-2021-28878

Understanding the technical aspects of CVE-2021-28878 is crucial for organizations looking to secure their systems and applications.

Vulnerability Description

The vulnerability in Rust's standard library arises from the incorrect handling of iterator calls within the Zip implementation. Specifically, multiple invocations of __iterator_get_unchecked() for the same index under certain conditions could result in a memory safety violation.

Affected Systems and Versions

The issue impacts Rust versions before 1.52.0, particularly when next_back() and next() are used together. Systems utilizing these functions in the affected versions may be vulnerable to memory safety violations.

Exploitation Mechanism

Attackers could potentially exploit CVE-2021-28878 by crafting malicious inputs or scenarios that trigger the erroneous behavior in the Zip implementation. This could lead to unauthorized access, data leaks, or other security breaches.

Mitigation and Prevention

To address the risks posed by CVE-2021-28878, organizations should implement immediate steps and adopt long-term security practices.

Immediate Steps to Take

Update Rust to version 1.52.0 or later to patch the vulnerability.
Monitor for any unusual activity or attempts to exploit the vulnerability.

Long-Term Security Practices

Regularly update dependencies and libraries to stay protected against known vulnerabilities.
Follow secure coding practices to minimize the likelihood of introducing similar issues in the future.

Patching and Updates

Stay informed about security advisories and patches released by Rust maintainers to address critical vulnerabilities like CVE-2021-28878.