CVE-2021-42343

Name: CVE-2021-42343
Creator: NVD / NIST
Published: 2021-10-26T11:15:07.8+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.88%

Last modified Jun 17, 2026

CVE-2021-42343 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 2.88% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

2.88%

85.0th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Anaconda	Dask	< 2021.10.0

References

https://docs.dask.org/en/latest/changelog.htmlRelease Notes, Vendor Advisory
https://github.com/dask/dask/tagsThird Party Advisory
https://github.com/dask/distributed/security/advisories/GHSA-hwqr-f3v9-hwxrThird Party Advisory
https://docs.dask.org/en/latest/changelog.htmlRelease Notes, Vendor Advisory
https://github.com/dask/dask/tagsThird Party Advisory
https://github.com/dask/distributed/security/advisories/GHSA-hwqr-f3v9-hwxrThird Party Advisory

Timeline

Published: Oct 26, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-42343?

How severe is CVE-2021-42343?

CVE-2021-42343 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.88% probability of exploitation in the next 30 days.

How do I fix CVE-2021-42343?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-42343?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST