# CVE-2020-9493: Java deserialization in Chainsaw


- **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
- **Fix available:** Yes
- **Published:** 16 Jun 2021
- **Updated:** 7 Oct 2026
- **Also known as:** CLSA-2026-1787931543, CLSA-2026-1790602996, CLSA-2026-1791960488, GHSA-prp9-9gxw-38j8

## What is CVE-2020-9493?

CVE-2020-9493 is a critical vulnerability in Apache Chainsaw, published on 16 Jun 2021. 

### Official description

A deserialization flaw was found in Apache Chainsaw versions prior to 2.1.0 which could lead to malicious code execution.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2020-9493?

It affects 3 products.


Products: Apache Chainsaw, Apache Log4j, Qos Reload4j.

## How do I fix CVE-2020-9493?

Upgrade to a fixed version.

## Is CVE-2020-9493 being exploited?

There is no known exploitation of CVE-2020-9493 in the wild and no public exploit code.

## Other vulnerabilities in Apache Chainsaw

- [CVE-2022-23307](https://insights.sbomify.com/CVE-2022-23307/): A deserialization flaw in the Chainsaw component of Log4j 1 can lead to malicious code execution. (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-9493 and fix it if it is affected.

What it is: CVE-2020-9493 is a critical vulnerability in Apache Chainsaw, published on 16 Jun 2021. 
Exploitation: There is no known exploitation of CVE-2020-9493 in the wild and no public exploit code.

Affected product: Apache Chainsaw. 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-2020-9493/ (Markdown: https://insights.sbomify.com/CVE-2020-9493/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-9493
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-9493
- OSV: https://osv.dev/vulnerability/CVE-2020-9493

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-9493/
Summaries are generated and may contain mistakes; the official description above is the record.