# CVE-2023-34188: Denial of service in n/a

> An attacker can cause a denial of service in the Mongoose HTTP server by sending requests with negative Content-Length headers, leading to an infinite loop.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 23 Jun 2023
- **Updated:** 28 Feb 2025
- **Also known as:** DEBIAN-CVE-2023-34188, GHSA-pcw9-xw4x-jgj3, UBUNTU-CVE-2023-34188

## What is CVE-2023-34188?

CVE-2023-34188 is a high-severity denial of service vulnerability in Cesanta Mongoose, published on 23 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The HTTP server in Mongoose before 7.10 accepts requests containing negative Content-Length headers. By sending a single attack payload over TCP, an attacker can cause an infinite loop in which the server continuously reparses that payload, and does not respond to any other requests.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input)

## Which versions are affected by CVE-2023-34188?

It affects 1 product.


Products: Cesanta Mongoose.

## How do I fix CVE-2023-34188?

Upgrade to a fixed version.

## Is CVE-2023-34188 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-34188 exists.

## Other vulnerabilities in Cesanta Mongoose

- [CVE-2022-25299](https://insights.sbomify.com/CVE-2022-25299/): Arbitrary File Write (critical 9.8)
- [CVE-2020-25756](https://insights.sbomify.com/CVE-2020-25756/): Memory corruption in n/a (critical 9.8)
- [CVE-2019-19307](https://insights.sbomify.com/CVE-2019-19307/): Integer overflow in n/a (critical 9.8)
- [CVE-2019-12951](https://insights.sbomify.com/CVE-2019-12951/): Memory corruption in n/a (critical 9.8)
- [CVE-2018-20353](https://insights.sbomify.com/CVE-2018-20353/): Use after free in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-34188 and fix it if it is affected.

What it is: CVE-2023-34188 is a high-severity denial of service vulnerability in Cesanta Mongoose, published on 23 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-34188 exists.

Affected product: Cesanta Mongoose. 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-2023-34188/ (Markdown: https://insights.sbomify.com/CVE-2023-34188/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-34188
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-34188
- OSV: https://osv.dev/vulnerability/CVE-2023-34188

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-34188/
Summaries are generated and may contain mistakes; the official description above is the record.