CVE-2021-21693Network attack vector

Arbitrary file creation via post-creation permission check

Published Nov 4, 2021 · Updated Aug 3, 2024

Incorrect authorization in Jenkins 2.318 and earlier and LTS 2.303.2 and earlier allows attackers to create files on the controller. The temporary-file creation path creates the requested file before agent-to-controller access control checks whether creation is permitted. Exploitation requires control of an agent process able to invoke the remote file operation, and the bounded impact is an unauthorized file write on the controller filesystem.

CVSS severity9.8
Critical
EPSS probability1.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Jenkins 2.318 and earlier and LTS 2.303.2 and earlier allows attackers to create files on the controller. The temporary-file creation path creates the requested file before agent-to-controller access control checks whether creation is permitted. Exploitation requires control of an agent process able to invoke the remote file operation, and the bounded impact is an unauthorized file write on the controller filesystem.

The record

CVE
CVE-2021-21693
Published
Nov 4, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
Jenkins
Classifications
CWE-863
Attack vector
network
Privileges
unauthenticated

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 privilegesunauthenticated

What is affected?

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

Published CVSS scores

7.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization

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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