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CVE-2021-43304

29
FAUCET Score

CVE-2021-43304 is a high-severity heap buffer overflow vulnerability in ClickHouse's LZ4 compression codec, affecting various ClickHouse and Debian ClickHouse products. It allows an authenticated attacker to execute arbitrary code or cause a denial of service by sending a specially crafted query, due to insufficient bounds checking during decompression. With a CVSS score of 8.8, this vulnerability presents a significant risk for confidentiality, integrity, and availability. There is currently no evidence of active exploitation, nor are there publicly available exploits or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 21.10.2.15CPE matchmatch criteria
cpe:2.3:a:clickhouse:clickhouse:*:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.65%
Probability of exploitation in next 30 days
EPSS Percentile
74.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0165 is in the 72nd percentile among its peer group of 17,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

jfrog.com / blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbms
ExploitThird Party Advisory
lists.debian.org / debian-lts-announce/2022/11/msg00002.html
Mailing ListThird Party Advisory