CVE-2021-43305 : What You Need to Know

CVE-2021-43305 pertains to a heap buffer overflow in Clickhouse's LZ4 compression codec due to a lack of verification in copy operations, potentially leading to arbitrary copy operations exceeding destination buffer limits.

Understanding CVE-2021-43305

Clickhouse's LZ4 compression codec is affected by a heap buffer overflow vulnerability, similar to CVE-2021-43304 but involving a different vulnerable copy operation.

What is CVE-2021-43305?

This CVE involves a heap buffer overflow in Clickhouse's LZ4 compression codec during the parsing of a malicious query. The issue arises from unchecked copy operations, specifically in the LZ4::decompressImpl loop, potentially leading to exceeding destination buffer limits.

The Impact of CVE-2021-43305

The vulnerability could allow attackers to execute arbitrary code or launch denial of service (DoS) attacks on systems running the affected Clickhouse versions.

Technical Details of CVE-2021-43305

Clickhouse's LZ4 compression codec vulnerability is detailed below:

Vulnerability Description

Heap buffer overflow in LZ4 compression codec during processing of a malicious query
Lack of verification in copy operations leading to potential buffer overflow

Affected Systems and Versions

Vendor: Yandex
Product: Clickhouse
Affected Versions: Unspecified, less than 21.10.2.15-stable (custom version)

Exploitation Mechanism

The vulnerability can be exploited by sending a specially crafted query to the affected Clickhouse system, triggering the heap buffer overflow condition.

Mitigation and Prevention

To address CVE-2021-43305, consider the following:

Immediate Steps to Take

Update the affected Clickhouse installations to a patched version
Monitor for any abnormal behavior indicating exploitation of the vulnerability

Long-Term Security Practices

Implement secure coding practices to prevent buffer overflows
Conduct regular security assessments and code reviews to identify vulnerabilities

Patching and Updates

Apply patches or updates provided by the vendor to remediate the vulnerability