# CVE-2020-13111: Denial of service in n/a

> Remote attackers can crash NaviServer by sending crafted chunked-transfer requests that trigger a negative size in memmove.

- **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:** No
- **Published:** 16 May 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-v99v-qgch-h5q5

## What is CVE-2020-13111?

CVE-2020-13111 is a high-severity denial of service vulnerability in n/a, published on 16 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

NaviServer 4.99.4 to 4.99.19 allows denial of service due to the nsd/driver.c ChunkedDecode function not properly validating the length of a chunk. A remote attacker can craft a chunked-transfer request that will result in a negative value being passed to memmove via the size parameter, causing the process to crash.

Weakness: CWE-787 (Out-of-bounds Write), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-13111?

It affects 1 product.


Products: Naviserver Project Naviserver.

## How do I fix CVE-2020-13111?

No fix has been published for CVE-2020-13111 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-13111 being exploited?

There is no known exploitation of CVE-2020-13111 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-13111 and fix it if it is affected.

What it is: CVE-2020-13111 is a high-severity denial of service vulnerability in n/a, published on 16 May 2020. 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-2020-13111 in the wild and no public exploit code.

Affected product: n/a. 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-2020-13111/ (Markdown: https://insights.sbomify.com/CVE-2020-13111/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-13111
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-13111
- OSV: https://osv.dev/vulnerability/CVE-2020-13111

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-13111/
Summaries are generated and may contain mistakes; the official description above is the record.