CVE-2021-21635Network attack vector

Stored XSS via unescaped JavaScript parameter reference

Published Mar 30, 2021 · Updated Aug 3, 2024

Stored XSS in Jenkins REST List Parameter Plugin 1.3.0 and earlier allows remote authenticated users to execute script in a victim's browser. The parameter renderer embeds a user-controlled parameter-name reference in JavaScript without escaping it, turning stored content into executable script. Exploitation requires Job/Configure permission and a victim who loads the affected view, exposing that viewer's Jenkins session to script actions.

CVSS severity5.4
Medium
EPSS probability8.76%
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 REST List Parameter Plugin 1.3.0 and earlier allows remote authenticated users to execute script in a victim's browser. The parameter renderer embeds a user-controlled parameter-name reference in JavaScript without escaping it, turning stored content into executable script. Exploitation requires Job/Configure permission and a victim who loads the affected view, exposing that viewer's Jenkins session to script actions.

The record

CVE
CVE-2021-21635
Published
Mar 30, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
REST List Parameter
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 30, 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 <=1.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Jenkins Project · REST List Parameterversion=unspecified <=1.3.0

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/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

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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

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Your stack

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