CVE-2021-42388: Clickhouse

High severity, CVSS 8.1. EPSS: 1.6% chance of exploitation in the next 30 days.

Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query. As part of the LZ4::decompressImpl() loop, a 16-bit unsigned user-supplied value ('offset') is read from the compressed data. The offset is later used in the length of a copy operation, without checking the lower bounds of the source of the copy operation.

Affected products

• Clickhouse Clickhouse: before 21.10.2.15 (fixed in 21.10.2.15)
• Debian Debian Linux: version 10.0 only

Published 2022-03-14. Last modified 2026-06-17.