# CVE-2021-43304: clickhouse: Heap buffer overflow in Clickhouse's LZ4 compression codec when parsing a malicious query

CVE-2021-43304 is fixed in clickhouse on 1 platform by DEBIAN-CVE-2021-43304 (version 18.16.1+ds-7.3), released March 14, 2022. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-43304
- Priority: High
- CVSS: 8.8 (high)
- EPSS: 0.0167
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 14, 2022

## Description

Heap buffer overflow in Clickhouse's LZ4 compression codec when parsing a malicious query. There is no verification that the copy operations in the LZ4::decompressImpl loop and especially the arbitrary copy operation wildCopy<copy_amount>(op, ip, copy_end), don’t exceed the destination buffer’s limits.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | clickhouse Debian 12.15 (bookworm) | 18.16.1+ds-7.3 | [DEBIAN-CVE-2021-43304](https://patchblox.com/security/data/fix/linux/debian-cve-2021-43304.md) | Mar 14, 2022 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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