# CVE-2020-26759: Arbitrary code execution in clickhouse-driver

> A malicious ClickHouse server can trigger a buffer overflow in the Python driver, leading to arbitrary code execution or crashes on the client.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Jan 2021
- **Updated:** 4 Aug 2024
- **Also known as:** BIT-clickhouse-2020-26759, DEBIAN-CVE-2020-26759, GHSA-vgv5-cxvh-vfxh, PYSEC-2021-61

## What is CVE-2020-26759?

CVE-2020-26759 is a critical memory corruption vulnerability in n/a, published on 6 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

clickhouse-driver before 0.1.5 allows a malicious clickhouse server to trigger a crash or execute arbitrary code (on a database client) via a crafted server response, due to a buffer overflow.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2020-26759?

4 open source packages ship an affected version, including clickhouse-driver and clickhouse. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `clickhouse-driver` | PyPI | All versions | 0.1.5 |
| `clickhouse-driver` | PyPI | All versions | 0.1.5 |
| `clickhouse-driver` | PyPI | All versions | 0.1.5 |
| `clickhouse` | Bitnami | All versions | 0.1.5 |

Products: Clickhouse-Driver Project Clickhouse-Driver.

## How do I fix CVE-2020-26759?

Upgrade clickhouse-driver to 0.1.5 or later.

## Is CVE-2020-26759 being exploited?

There is no known exploitation of CVE-2020-26759 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-26759 and fix it if it is affected.

What it is: CVE-2020-26759 is a critical memory corruption vulnerability in n/a, published on 6 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-26759 in the wild and no public exploit code.

Affected packages and fixed versions:
- clickhouse-driver (PyPI): affected all versions; fixed in 0.1.5
- clickhouse-driver (PyPI): affected all versions; fixed in 0.1.5
- clickhouse-driver (PyPI): affected all versions; fixed in 0.1.5
- clickhouse (Bitnami): affected all versions; fixed in 0.1.5

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-2020-26759/ (Markdown: https://insights.sbomify.com/CVE-2020-26759/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26759
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26759
- OSV: https://osv.dev/vulnerability/CVE-2020-26759

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-26759/
Summaries are generated and may contain mistakes; the official description above is the record.