CVE-2021-21620Network attack vector

Claim changes via missing POST requirement

Published Feb 24, 2021 · Updated Aug 3, 2024

Cross-site request forgery in Jenkins Claim Plugin 2.18.1 and earlier allows remote attackers to change claims via crafted requests. The claim-assignment form endpoint accepts non-POST requests, so a cross-site page can cause a victim's browser to submit the action without an anti-CSRF method gate. Exploitation requires a logged-in Jenkins victim to visit attacker-controlled content and changes claim assignments without exposing data or interrupting service.

CVSS severity4.3
Medium
EPSS probability1.64%
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

Cross-site request forgery in Jenkins Claim Plugin 2.18.1 and earlier allows remote attackers to change claims via crafted requests. The claim-assignment form endpoint accepts non-POST requests, so a cross-site page can cause a victim's browser to submit the action without an anti-CSRF method gate. Exploitation requires a logged-in Jenkins victim to visit attacker-controlled content and changes claim assignments without exposing data or interrupting service.

The record

CVE
CVE-2021-21620
Published
Feb 24, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
Jenkins Claim Plugin
Classifications
CWE-352, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 24, 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 <=2.18.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Jenkins Project · Jenkins Claim Pluginversion=unspecified <=2.18.1

Published CVSS scores

4.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
4.3NVDAV:N/AC:M/Au:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1189Drive-by Compromise

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