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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-21658
• https://www.jenkins.io/security/advisory/2021-05-25/#SECURITY-2340
• http://www.openwall.com/lists/oss-security/2021/05/25/3
• jenkinsci/nuget-plugin@542bf38
• jenkinsci/nuget-plugin@c8ed4cb