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CVE-2021-42390

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-03-14 · updated 2026-06-17
• Weakness: CWE-369

Description

Divide-by-zero in Clickhouse's DeltaDouble 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.

Affected products

• ClickHouse: before 21.10.2.15 — fixed in 21.10.2.15

How to fix

Upgrade to a fixed version: ClickHouse 21.10.2.15. Check the vendor advisory for mitigations.

References

• https://jfrog.com/blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbms
• https://jfrog.com/blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbms

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