Is CVE-2021-42391 in the CISA KEV catalog?

No. CVE-2021-42391 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-42391?

CVE-2021-42391 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2021-42391?

CVE-2021-42391 has an EPSS score of 1.35% (68th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-42391?

Upgrade clickhouse to 21.10.2.15 or later.

CVE & CISA-KEV Catalog

CVE-2021-42391

MEDIUM

6.5

CVSS v3

NVD

Description

Divide-by-zero in Clickhouse's Gorilla 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.

CWE-369

How to fix

Remediation Available

clickhouseNVD

Affected:< 21.10.2.15Fixed in:21.10.2.15CVE-2021-42391derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

1.35%probability of exploitation in 30 days

68thpercentile

Moderate risk: more likely to be exploited than 68% of all known CVEs.

References

Exploit1

jfrog.com

Related Vulnerabilities

Other CWE-369 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2012-0207	High	7.5	20%	-	Fix
CVE-2017-8537	Medium	5.5	17%	-	-
CVE-2017-8536	Medium	5.5	17%	-	-
CVE-2017-8535	Medium	5.5	17%	-	-
CVE-2007-2237	Medium	5.5	15%	-	-
CVE-2025-0317	High	7.5	13%	-	-

Embed a live status badge for CVE-2021-42391

Markdown

[![CVE-2021-42391](https://tridentstack.com/cve/badge/CVE-2021-42391.svg)](https://tridentstack.com/cve/CVE-2021-42391)

HTML

<a href="https://tridentstack.com/cve/CVE-2021-42391"><img src="https://tridentstack.com/cve/badge/CVE-2021-42391.svg" alt="CVE-2021-42391"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-06-25.