CVE-2021-42387 json
Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query.
published 2022-03-14 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-29358
- cvss
- 8.1
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.6%
- EPSS 1.6% chance of exploitation in 30 days, percentile 75%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- yandex clickhouse 21.10.2.15-stable
- clickhouse Debian 12 18.16.1+ds-7.3
debian advisories DEBIAN-CVE-2021-42387
- clickhouse Ubuntu 20.04 LTS 18.16.1+ds-7ubuntu0.1
ubuntu advisories UBUNTU-CVE-2021-42387
Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
Exploit prediction
1.57% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- jfrog.com https://jfrog.com/blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbms referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 8.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H |
| NVD | 2.0 | 5.5 | AV:N/AC:L/Au:S/C:P/I:N/A:P |
Affected products
- yandex clickhouse
Classification
- Weakness
-
- CWE-125 Out-of-bounds Read
References
-
jfrog.com
/blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbms
exploit, third-party-advisory
-
lists.debian.org
/debian-lts-announce/2022/11/msg00002.html
mailing-list, third-party-advisory
Sources
- CVE List CVE-2021-42387
- NVD CVE-2021-42387
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.