# CVE-2020-36661: Kong lua-multipart multipart.lua is_header redos

> An attacker can cause denial of service in Kong lua-multipart via inefficient regular expression complexity in the is_header function.

- **Severity:** Low 3.5 (`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Feb 2023
- **Updated:** 24 Mar 2025
- **Also known as:** GHSA-wjp8-5g4j-4rjj

## What is CVE-2020-36661?

CVE-2020-36661 is a low-severity denial of service vulnerability in Kong lua-multipart, published on 12 Feb 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability was found in Kong lua-multipart 0.5.8-1. It has been declared as problematic. This vulnerability affects the function is_header of the file src/multipart.lua. The manipulation leads to inefficient regular expression complexity. Upgrading to version 0.5.9-1 is able to address this issue. The patch is identified as d632e5df43a2928fd537784a99a79dec288bf01b. It is recommended to upgrade the affected component. VDB-220642 is the identifier assigned to this vulnerability.

Weakness: CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2020-36661?

It affects 1 product.


Products: Konghq Multipart.

## How do I fix CVE-2020-36661?

No fix has been published for CVE-2020-36661 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-36661 being exploited?

There is no known exploitation of CVE-2020-36661 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-36661 and fix it if it is affected.

What it is: CVE-2020-36661 is a low-severity denial of service vulnerability in Kong lua-multipart, published on 12 Feb 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-36661 in the wild and no public exploit code.

Affected product: Kong lua-multipart. 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-2020-36661/ (Markdown: https://insights.sbomify.com/CVE-2020-36661/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-36661
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-36661
- OSV: https://osv.dev/vulnerability/CVE-2020-36661

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-36661/
Summaries are generated and may contain mistakes; the official description above is the record.