CVE-2021-42387
Heap out-of-bounds read in Clickhouse's LZ4 compression codec when parsing a malicious query.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.57%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 8.1 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- EPSS
- 1.57% probability · 75th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Affected
- clickhouse/clickhouse · debian/debian linux
- Source
- reefs@jfrog.com
EPSS 1.6% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://jfrog.com/blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbmsExploit, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/11/msg00002.htmlMailing List, Third Party Advisory
- https://jfrog.com/blog/7-rce-and-dos-vulnerabilities-found-in-clickhouse-dbmsExploit, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/11/msg00002.htmlMailing List, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.