CVE-2021-42391 Explained : Impact and Mitigation
Learn about CVE-2021-42391, a Clickhouse vulnerability allowing divide-by-zero exploitation. Find mitigation steps and impacted versions in this detailed overview.
Understanding CVE-2021-42391
What is CVE-2021-42391?
Clickhouse's Gorilla compression codec is vulnerable to a divide-by-zero issue when processing a malicious query, leading to potential exploitation due to the unchecked first byte in a modulo operation.
The Impact of CVE-2021-42391
This vulnerability has a CVSS base score of 6.5, with a LOW attack complexity over the network. It poses a HIGH availability impact but does not affect confidentiality or integrity, requiring LOW privileges and no user interaction.
Technical Details of CVE-2021-42391
Vulnerability Description
The vulnerability in Clickhouse's Gorilla compression codec allows an attacker to trigger a divide-by-zero situation via a specifically crafted query.
Affected Systems and Versions
- Affected Product: Clickhouse
- Vendor: Yandex
- Vulnerable Version: < 21.10.2.15-stable (unspecified custom version)
Exploitation Mechanism
The issue arises from the unvalidated first byte of the compressed buffer used in a modulo operation, enabling a malicious actor to execute arbitrary code or cause a denial of service.
Mitigation and Prevention
Immediate Steps to Take
- Update Clickhouse to a patched version above 21.10.2.15-stable
- Monitor network traffic for any suspicious activities
- Apply security patches and configurations promptly
Long-Term Security Practices
- Conduct regular security audits and code reviews
- Implement secure coding practices to prevent similar vulnerabilities
- Educate users and developers on secure query handling
Patching and Updates
Develop and follow a robust patch management plan to ensure timely application of security patches and updates.