CVE-2021-21699Network attack vector

Stored XSS via unescaped parameter names

Published Nov 12, 2021 · Updated Aug 3, 2024

Stored XSS in Jenkins Active Choices Plugin 2.5.6 and earlier allows remote authenticated users to execute script in another user's browser. The CascadeChoiceParameter and DynamicReferenceParameter Jelly views interpolate parameter names into JavaScript and HTML identifiers without escaping. Job/Configure permission is required to store a crafted name, and a subsequent viewer must open a rendered parameter page for the script to execute.

CVSS severity5.4
Medium
EPSS probability88.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Jenkins Active Choices Plugin 2.5.6 and earlier allows remote authenticated users to execute script in another user's browser. The CascadeChoiceParameter and DynamicReferenceParameter Jelly views interpolate parameter names into JavaScript and HTML identifiers without escaping. Job/Configure permission is required to store a crafted name, and a subsequent viewer must open a rendered parameter page for the script to execute.

The record

CVE
CVE-2021-21699
Published
Nov 12, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
Active Choices Plugin
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 12, 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 <=2.5.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Jenkins Project · Active Choices Pluginversion=unspecified <=2.5.6

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

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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