CVE-2021-21618Network attack vector

Stored XSS via unescaped past-build parameters

Published Feb 24, 2021 · Updated Aug 3, 2024

Stored XSS in Jenkins Repository Connector Plugin 2.0.2 and earlier allows remote authenticated users to execute script in a viewer's browser. Past-build views render attacker-controlled parameter names and descriptions without escaping them. Item/Configure permission is required to store the payload, and a viewer must open the affected build page for browser-side code execution.

CVSS severity5.4
Medium
EPSS probability81.77%
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 Repository Connector Plugin 2.0.2 and earlier allows remote authenticated users to execute script in a viewer's browser. Past-build views render attacker-controlled parameter names and descriptions without escaping them. Item/Configure permission is required to store the payload, and a viewer must open the affected build page for browser-side code execution.

The record

CVE
CVE-2021-21618
Published
Feb 24, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
Repository Connector Plugin
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

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

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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 <=2.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Jenkins Project · Repository Connector Pluginversion=unspecified <=2.0.2

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')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

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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