CVE-2021-21647Network attack vector

Unauthorized build scheduling via missing permission check

Published Apr 21, 2021 · Updated Aug 3, 2024

Missing authorization in Jenkins Project CloudBees CD Plugin 1.1.21 and earlier allows remote authenticated users to schedule builds. An HTTP endpoint schedules a project build after checking Item/Read access but omits the required Item/Build permission check. The gate is Item/Read access to the target project, and successful exploitation starts that project's configured build.

CVSS severity4.3
Medium
EPSS probability1.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Missing authorization in Jenkins Project CloudBees CD Plugin 1.1.21 and earlier allows remote authenticated users to schedule builds. An HTTP endpoint schedules a project build after checking Item/Read access but omits the required Item/Build permission check. The gate is Item/Read access to the target project, and successful exploitation starts that project's configured build.

The record

CVE
CVE-2021-21647
Published
Apr 21, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
CloudBees CD Plugin
Classifications
T1053
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 21, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <=1.1.21

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Jenkins Project · CloudBees CD Pluginversion=unspecified <=1.1.21

Published CVSS scores

4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1053Scheduled Task/Job

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo