CVE-2021-29626 Explained : Impact and Mitigation

In FreeBSD versions including 13.0-STABLE before n245117, 12.2-STABLE before r369551, 11.4-STABLE before r369559, 13.0-RC5 before p1, 12.2-RELEASE before p6, and 11.4-RELEASE before p9, a vulnerability exists where copy-on-write logic fails to invalidate shared memory page mappings between multiple processes. This flaw allows an unprivileged process to maintain a mapping after it is freed, enabling access to private data from other processes or the kernel.

Understanding CVE-2021-29626

This section provides insights into the nature of the vulnerability and its potential impact.

What is CVE-2021-29626?

The CVE-2021-29626 vulnerability in FreeBSD arises from a failure to properly invalidate shared memory page mappings between processes. This allows an unauthorized process to retain mappings to access private data from other processes or the kernel.

The Impact of CVE-2021-29626

The impact of this vulnerability is significant as it permits an unprivileged process to read sensitive data from other processes or the kernel, potentially leading to unauthorized access and data breaches.

Technical Details of CVE-2021-29626

Here we delve into the specific technical aspects of the CVE-2021-29626 vulnerability.

Vulnerability Description

The vulnerability involves an issue in the copy-on-write logic that results in the persistence of shared memory page mappings, enabling unauthorized access to private data.

Affected Systems and Versions

FreeBSD versions including 13.0-STABLE before n245117, 12.2-STABLE before r369551, 11.4-STABLE before r369559, 13.0-RC5 before p1, 12.2-RELEASE before p6, and 11.4-RELEASE before p9 are affected by this vulnerability.

Exploitation Mechanism

Exploitation of this vulnerability involves an unprivileged process maintaining mappings to read private data from other processes or the kernel, leading to potential data disclosure.

Mitigation and Prevention

To secure systems against CVE-2021-29626, immediate steps should be taken along with long-term security practices.

Immediate Steps to Take

Immediately update the affected FreeBSD versions to patched releases and monitor for any suspicious activities that may indicate exploitation of the vulnerability.

Long-Term Security Practices

Implement comprehensive security measures such as access control, privilege separation, and regular security audits to enhance overall system security.

Patching and Updates

Regularly apply security patches and updates provided by FreeBSD to address known vulnerabilities and strengthen system defenses.