CVE-2021-21300 : What You Need to Know
Learn about CVE-2021-21300, a critical vulnerability in Git that allows malicious repositories to execute remote code during cloning. Understand the impact, affected versions, and mitigation steps.
This CVE involves a vulnerability in Git that allows malicious repositories to execute remote code while cloning. The issue affects older versions of Git and has been patched in newer releases. Here's what you need to know:
Understanding CVE-2021-21300
Git, an open-source distributed revision control system, is impacted by a security flaw that allows specially crafted repositories to trigger the execution of scripts during the cloning process. This vulnerability can be exploited on case-insensitive file systems like NTFS, HFS+, or APFS, which are default on Windows and macOS.
What is CVE-2021-21300?
The vulnerability arises from the interaction between symbolic links and clean/smudge filters (e.g., Git LFS) in Git repositories. By leveraging this issue, threat actors can execute arbitrary code on a victim's system when cloning a malicious repository.
The Impact of CVE-2021-21300
The impact of this vulnerability is rated as 'HIGH' with a base score of 8 according to CVSS v3.1 metrics. The confidentiality and integrity of affected systems are at significant risk, highlighting the critical nature of this security issue.
Technical Details of CVE-2021-21300
The following technical aspects are crucial to understanding and addressing CVE-2021-21300:
Vulnerability Description
The vulnerability allows malicious repositories to execute remote code during the cloning process, posing a severe threat to the security of Git users.
Affected Systems and Versions
Git versions ranging from 2.14.2 to 2.30.0 are impacted by this vulnerability. It is essential to update Git to the patched versions to mitigate the risk.
Exploitation Mechanism
Attackers exploit the vulnerability by creating repositories with symbolic links and clean/smudge filters, tricking Git into executing arbitrary scripts during the cloning operation.
Mitigation and Prevention
Protecting systems from CVE-2021-21300 requires immediate actions and long-term security practices:
Immediate Steps to Take
Disable symbolic link support in Git and ensure that no clean/smudge filters are globally configured before cloning repositories. Additionally, refrain from cloning repositories from untrusted sources.
Long-Term Security Practices
Regularly update Git to the latest patched versions and follow secure coding practices to mitigate similar vulnerabilities in the future.
Patching and Updates
Ensure that Git is updated to versions 2.30.1, 2.29.3, 2.28.1, or other fixed releases to address CVE-2021-21300 and prevent exploitation.