CVE-2021-21689Network attack vector

Controller file read and write via unchecked extraction

Published Nov 4, 2021 · Updated Aug 3, 2024

Missing access control in Jenkins 2.318 and earlier and LTS 2.303.2 and earlier allows attackers controlling agents to read or write controller files. FilePath#unzip and FilePath#untar accept archive extraction requests from agent processes without applying the controller file-path authorization filter. Control of a connected agent is required; successful use exposes controller files to arbitrary reads and writes without interrupting service.

CVSS severity9.1
Critical
EPSS probability1.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing access control in Jenkins 2.318 and earlier and LTS 2.303.2 and earlier allows attackers controlling agents to read or write controller files. FilePath#unzip and FilePath#untar accept archive extraction requests from agent processes without applying the controller file-path authorization filter. Control of a connected agent is required; successful use exposes controller files to arbitrary reads and writes without interrupting service.

The record

CVE
CVE-2021-21689
Published
Nov 4, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
Jenkins
Classifications
T1005, T1565.001
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Nov 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <=2.318
  2. Affected versionversion=unspecified <=LTS 2.303.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Jenkins Project · Jenkinsversion=unspecified <=2.318; version=unspecified <=LTS 2.303.2

Published CVSS scores

6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1005Data from Local System
T1565.001Stored Data Manipulation

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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