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NVD / CVE Program· CNA JFROG

CVE-2021-42388: Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query.

HighCVSS 8.1 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.5% (FIRST EPSS); higher than 75.7% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: clickhouse (Debian:10) 18.16.1+ds-4+deb10u1; clickhouse (Debian:12) 18.16.1+ds-7.3.

Low priority for now. Upgrade to clickhouse (Debian:10) 18.16.1+ds-4+deb10u1; clickhouse (Debian:12) 18.16.1+ds-7.3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query. As part of the LZ4::decompressImpl() loop, a 16-bit unsigned user-supplied value ('offset') is read from the compressed data. The offset is later used in the length of a copy operation, without checking the lower bounds of the source of the copy operation.

Published
Mar 14, 2022
Updated
Jun 17, 2026
EPSS
1.5% · 75th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.5%

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
clickhouseclickhouse
debiandebian linux

Versions reported by the vendor

Affected version ranges reported by the assigning authority (JFROG). Independent of NVD's CPE analysis and usually ahead of it.

  • yandex clickhouse

    • unspecified and later · before 21.10.2.15-stableaffected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • clickhouse clickhousebefore 21.10.2.15
  • debian debian linux10.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:10clickhousebefore 18.16.1+ds-4+deb10u118.16.1+ds-4+deb10u1
Debian:12clickhousebefore 18.16.1+ds-7.318.16.1+ds-7.3

Same product

clickhouse: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-16535In all versions of ClickHouse before 19.14, an OOB read, OOB write and integer underflow in decompression algorithms can be used to achieve…
    40Plan
  • CVE-2018-14671In ClickHouse before 18.10.3, unixODBC allowed loading arbitrary shared objects from the file system which led to a Remote Code Execution…
    40Plan
  • CVE-2018-14670Incorrect configuration in deb package in ClickHouse before 1.1.54131 could lead to unauthorized use of the database.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2019-15024Dec 30, 2019 · In all versions of ClickHouse before 19.14.3, an attacker having write access to ZooKeeper and who is able to run a custom server available…
    26Monitor
  • ← EarlierCVE-2021-42387Mar 14, 2022 · Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query.
    32Monitor
  • Later →CVE-2021-42389Mar 14, 2022 · Divide-by-zero in Clickhouse's Delta compression codec when parsing a malicious query.
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:clickhouse18.16.1+ds-7.3 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records