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CRITICAL severity

CVE-2021-21658 — nuget

CRITICALFix: jenkinsci/nuget-plugin@542bf38

CVE-2021-21658 is a critical-severity (CVSS 9.1) vulnerability in org.jenkins-ci.plugins:nuget. A fix is available for org.jenkins-ci.plugins:nuget — see the affected versions and patch details below.

XML external entity vulnerability in Jenkins Nuget Plugin

Also known asGHSA-p674-hh8x-rv5h
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs75th percentile — riskier than 75% of all scored CVEsHighest risk
0.19%0.80%1.42%2.04%0.7%1.5%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
☕org.jenkins-ci.plugins:nuget

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Jenkins Nuget Plugin 1.0 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks. This XML parser is used for the "Build on NuGet updates" feature.

This allows attackers with the ability to control the contents of the packages.config file in a workspace to have Jenkins parse a crafted XML document that uses external entities for extraction of secrets from the Jenkins controller or server-side request forgery.

Jenkins Nuget Plugin 1.1 disables external entity resolution for its XML parser.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.plugins:nugetall versions1.1org.jenkins-ci.plugins:nuget:1.1

Affected Products

1 product · 1 configurations
Application
nugetjenkins
≤ 1.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jenkins-ci.plugins:nuget, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.jenkins-ci.plugins:nuget to 1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21658 is resolved across your whole dependency graph.

  3. Workarounds

    Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Frequently Asked Questions

Jenkins Nuget Plugin 1.0 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks. This XML parser is used for the \"Build on NuGet updates\" feature. This allows attackers with the ability to control the contents of the `packages.config` file in a workspace to have Jenkins parse a crafted XML document that uses external entities for extraction of secrets from the Jenkins controller or server-side request forgery. Jenkins Nuget Plugin 1.1 disables external entity resolution for its XML parser.
O3 Security · Impact-Aware SCA

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CVE-2021-21658: nuget SSRF — Fixed in 1.1