CVE-2021-21658Network attack vector

Secret extraction or SSRF via XML entities

Published May 25, 2021 · Updated Aug 3, 2024

XML external entity injection in Jenkins Nuget Plugin 1.0 and earlier allows attackers to extract controller secrets or cause SSRF. NugetPackageCheckerVisitor creates a default DocumentBuilderFactory and parses workspace packages.config files without disabling DOCTYPE declarations or external entity resolution. Exploitation requires control of a packages.config file processed by the Build on NuGet updates feature, exposing controller secrets or making controller-originated requests.

CVSS severity9.1
Critical
EPSS probability1.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XML external entity injection in Jenkins Nuget Plugin 1.0 and earlier allows attackers to extract controller secrets or cause SSRF. NugetPackageCheckerVisitor creates a default DocumentBuilderFactory and parses workspace packages.config files without disabling DOCTYPE declarations or external entity resolution. Exploitation requires control of a packages.config file processed by the Build on NuGet updates feature, exposing controller secrets or making controller-originated requests.

The record

CVE
CVE-2021-21658
Published
May 25, 2021
Updated
Aug 3, 2024
Vendor
Jenkins Project
Product
Nuget Plugin
Classifications
CWE-611, T1005
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. May 25, 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 <=1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Jenkins Project · Nuget Pluginversion=unspecified <=1.0

Published CVSS scores

6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-611Improper Restriction of XML External Entity Reference
T1005Data from Local System

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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