CVE-2023-47118: Heap buffer overflow in T64 codec decompression

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-12-20 · updated 2026-06-17
Weakness: CWE-122

Description

ClickHouse® is an open-source column-oriented database management system that allows generating analytical data reports in real-time. A heap buffer overflow issue was discovered in ClickHouse server. An attacker could send a specially crafted payload to the native interface exposed by default on port 9000/tcp, triggering a bug in the decompression logic of T64 codec that crashes the ClickHouse server process. This attack does not require authentication. Note that this exploit can also be triggered via HTTP protocol, however, the attacker will need a valid credential as the HTTP authentication take places first. This issue has been fixed in version 23.10.2.13-stable, 23.9.4.11-stable, 23.8.6.16-lts and 23.3.16.7-lts.

Affected products

ClickHouse: from 23.3 before 23.3.16.7; from 23.8 before 23.8.6.16; from 23.9 before 23.9.4.11; from 23.10 before 23.10.2.13 — fixed in 23.10.2.13, 23.3.16.7, 23.8.6.16, 23.9.4.11
Clickhouse Cloud: before 23.9.2.47475 — fixed in 23.9.2.47475

How to fix

Upgrade to a fixed version: ClickHouse 23.10.2.13, 23.3.16.7, 23.8.6.16, 23.9.4.11; Clickhouse Cloud 23.9.2.47475. Check the vendor advisory for mitigations.

References

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