Jenkins Assembla Plugin XXE (v1.4 and below)
CVE-2026-57303 Published on June 24, 2026
Jenkins Assembla Plugin 1.4 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks, allowing attackers able to control the responses of the configured Assembla server to extract secrets from the Jenkins controller or perform server-side request forgery.
Vulnerability Analysis
CVE-2026-57303 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity, and no impact on availability.
Weakness Type
What is a SSRF Vulnerability?
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
CVE-2026-57303 has been classified to as a SSRF vulnerability or weakness.
Products Associated with CVE-2026-57303
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Affected Versions
Jenkins Project Jenkins Assembla Plugin:- Before and including 1.4 is affected.