What is CVE-2021-42389?

CVE-2021-42389 is a medium-severity vulnerability in Clickhouse, classified under Divide By Zero. CVSS score: 6.5/10. Published 2022-03-14.

How severe is CVE-2021-42389?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Clickhouse

CVE-2021-42389

Divide-by-zero in Clickhouse's Delta compression codec when parsing a malicious query. The first byte of the compressed buffer is used in a modulo operation without being checked for 0.

Published 2022-03-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.013 (68.4th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 68.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Clickhouse
Yandex Clickhouse — versions unspecified

Weakness classification (CWE)

CWE-369 — Divide By Zero

References

jfrog.com/blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbms (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-42389?: CVE-2021-42389 is a medium-severity vulnerability in Clickhouse, classified under Divide By Zero. CVSS score: 6.5/10. Published 2022-03-14.
How severe is CVE-2021-42389?: Medium severity. CVSS v3 base score is 6.5 out of 10.