Jenkins Swarm Plugin allows clients to auto-discover Jenkins instances on the same network through a UDP discovery request. Responses to this request are XML documents.

Swarm Plugin does not configure the XML parser in a way that would prevent XML External Entity (XXE) processing. This allows unauthenticated attackers on the same network to have Swarm clients parse a maliciously crafted XML response that uses external entities to read arbitrary files from the Swarm client or denial-of-service attacks.

As of publication of this advisory, there is no fix.

References

• https://nvd.nist.gov/vuln/detail/CVE-2019-10309
• https://jenkins.io/security/advisory/2019-04-30/#SECURITY-1252
• http://www.openwall.com/lists/oss-security/2019/04/30/5
• https://www.talosintelligence.com/vulnerability_reports/TALOS-2019-0783
• https://web.archive.org/web/20200227073756/http://www.securityfocus.com/bid/108159