# CVE-2021-43305: Memory corruption in clickhouse

> A heap buffer overflow in ClickHouse's LZ4 codec allows attackers to execute arbitrary code or cause denial of service via malicious queries.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Mar 2022
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-43305, GHSA-rjm8-hjq2-73j6, UBUNTU-CVE-2021-43305

## What is CVE-2021-43305?

CVE-2021-43305 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 14 Mar 2022. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Heap buffer overflow in Clickhouse's LZ4 compression codec when parsing a malicious query. There is no verification that the copy operations in the LZ4::decompressImpl loop and especially the arbitrary copy operation wildCopy<copy_amount>(op, ip, copy_end), don’t exceed the destination buffer’s limits. This issue is very similar to CVE-2021-43304, but the vulnerable copy operation is in a different wildCopy call.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2021-43305?

It affects 2 products.


Products: Clickhouse Clickhouse, Debian Debian Linux.

## How do I fix CVE-2021-43305?

Apply the vendor's patch.

## Is CVE-2021-43305 being exploited?

There is no known exploitation of CVE-2021-43305 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2019-16535](https://insights.sbomify.com/CVE-2019-16535/): Memory corruption in ClickHouse (critical 9.8)
- [CVE-2018-14670](https://insights.sbomify.com/CVE-2018-14670/): Missing authorization in ClickHouse (critical 9.8)
- [CVE-2018-14671](https://insights.sbomify.com/CVE-2018-14671/): Code injection in ClickHouse (critical 9.8)
- [CVE-2021-43304](https://insights.sbomify.com/CVE-2021-43304/): Memory corruption in clickhouse (high 8.8)
- [CVE-2018-14668](https://insights.sbomify.com/CVE-2018-14668/): Server-side request forgery in ClickHouse (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43305 and fix it if it is affected.

What it is: CVE-2021-43305 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 14 Mar 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43305 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-43305/ (Markdown: https://insights.sbomify.com/CVE-2021-43305/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43305
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43305
- OSV: https://osv.dev/vulnerability/CVE-2021-43305

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43305/
Summaries are generated and may contain mistakes; the official description above is the record.