# CVE-2020-8437: Null dereference in n/a

> A remote attacker can cause a denial of service in uTorrent by exploiting a null pointer dereference in the bencoding parser.

- **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:** 2 Mar 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-f77w-22mg-cg9g

## What is CVE-2020-8437?

CVE-2020-8437 is a high-severity vulnerability in n/a, published on 2 Mar 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The bencoding parser in BitTorrent uTorrent through 3.5.5 (build 45505) misparses nested bencoded dictionaries, which allows a remote attacker to cause a denial of service.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2020-8437?

It affects 1 product.


Products: Bittorrent Utorrent.

## How do I fix CVE-2020-8437?

No fix has been published for CVE-2020-8437 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-8437 being exploited?

There is no known exploitation of CVE-2020-8437 in the wild and no public exploit code.

Public exploit code:

- Exploit for uTorrent vulnerability CVE-2020-8437 by mavlevin (github_poc): https://github.com/mavlevin/uTorrent-CVE-2020-8437

## Other vulnerabilities in n/a

- [CVE-2018-25044](https://insights.sbomify.com/CVE-2018-25044/): uTorrent Guest Account privileges management (medium 6.3)
- [CVE-2018-25042](https://insights.sbomify.com/CVE-2018-25042/): uTorrent memory corruption (medium 5.0)
- [CVE-2018-25043](https://insights.sbomify.com/CVE-2018-25043/): uTorrent PRNG improper authentication (medium 5.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-8437 and fix it if it is affected.

What it is: CVE-2020-8437 is a high-severity vulnerability in n/a, published on 2 Mar 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-2020-8437 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-2020-8437/ (Markdown: https://insights.sbomify.com/CVE-2020-8437/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8437
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8437
- OSV: https://osv.dev/vulnerability/CVE-2020-8437

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8437/
Summaries are generated and may contain mistakes; the official description above is the record.