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CVE-2021-42387

Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query. As...

8.1 HighFix available

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 upper bounds of the source of the copy operation.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
High

Exploit likelihood

1.57%Up 0.7 points since Mar 15, 2022
90%50%10%1%

What each source reports

NVD Score used 8.1

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 upper bounds of the source of the copy operation.

Record
CVE-2021-42387
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
CVSS 2.0
5.5 MediumAV:N/AC:L/Au:S/C:P/I:N/A:P
Weakness
CWE-125
Updated
2026-11-02
CVE List No score

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 upper bounds of the source of the copy operation.

Record
CVE-2021-42387
Weakness
CWE-125
Updated
2026-11-02
EUVDEUVD-2021-29358 No score

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 upper bounds of the source of the copy operation.

Record
EUVD-2021-29358
Updated
2026-11-03
GitHub AdvisoriesGHSA-cf9g-639p-3wvv 8.1

Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query. As...

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 upper bounds of the source of the copy operation.

Record
GHSA-cf9g-639p-3wvv
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Weakness
CWE-125
Updated
2026-11-02
OSV 8.1

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 upper bounds of the source of the copy operation.

Record
CVE-2021-42387
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2021-42387 8.1

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 upper bounds of the source of the copy operation.

Record
DEBIAN-CVE-2021-42387
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-42387 8.1

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 upper bounds of the source of the copy operation.

Record
UBUNTU-CVE-2021-42387
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Updated
2026-11-02
OSVUSN-6933-1 No score

clickhouse vulnerabilities

It was discovered that ClickHouse incorrectly handled memory, leading to a heap out-of-bounds data read. An attacker could possibly use this issue to cause a denial of service, or leak sensitive information. (CVE-2021-42387, CVE-2021-41388)

It was discovered that ClickHouse incorrectly handled memory, leading to a heap-based buffer overflow. An attacker could possibly use this issue to cause a denial of service, or execute arbitrary code. (CVE-2021-43305)

Record
USN-6933-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
clickhouse
Debian:12
before 18.16.1+ds-7.3
18.16.1+ds-7.3
clickhouse
Debian:10
before 18.16.1+ds-4+deb10u1, plus listed versions
18.16.1+ds-4
18.16.1+ds-4+deb10u1
clickhouse
Ubuntu:20.04:LTS
before 18.16.1+ds-7ubuntu0.1, plus listed versions
18.16.1+ds-518.16.1+ds-5ubuntu118.16.1+ds-5ubuntu218.16.1+ds-6ubuntu118.16.1+ds-7
18.16.1+ds-7ubuntu0.1

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-42387 is a high vulnerability (CVSS 8.1) in Clickhouse, published March 14, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.57%, the 75th percentile. Fixed in clickhouse 18.16.1+ds-7.3.

References

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