CVE-2021-42343Network attack vector

Remote code execution via exposed worker ports

Published Oct 26, 2021 · Updated Aug 4, 2024

Dask distributed before 2021.10.0 allows remote attackers to execute code via workers listening on externally reachable high ports. LocalCluster and the Client default configure worker and nanny hosts without forwarding the requested localhost host value, causing listeners to bind externally. Exploitation requires a single-machine cluster with an exposed worker port; a successful connection can provide remote code execution, while standard firewalls or non-LocalCluster deployments block the path.

CVSS severity9.8
Critical
EPSS probability3.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Dask distributed before 2021.10.0 allows remote attackers to execute code via workers listening on externally reachable high ports. LocalCluster and the Client default configure worker and nanny hosts without forwarding the requested localhost host value, causing listeners to bind externally. Exploitation requires a single-machine cluster with an exposed worker port; a successful connection can provide remote code execution, while standard firewalls or non-LocalCluster deployments block the path.

The record

CVE
CVE-2021-42343
Published
Oct 26, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-668, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8GitLab Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3GitLab Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
7.5GitLab Advisory DatabaseAV:N/AC:M/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-668Exposure of Resource to Wrong Sphere
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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