Executive brief
The Bitbucket Server Integration Plugin for Jenkins, used by organizations to integrate source control with their CI/CD pipelines, contains an OAuth authorization flaw that allows attackers to hijack the login flow. By manipulating the OAuth callback URL, an attacker can intercept the authentication token and gain unauthorized access to Jenkins with the victim's privileges, potentially compromising builds, deployments, and sensitive source code.
Technical details
The vulnerability is an OAuth authorization hijacking attack in the Jenkins Bitbucket Server Integration Plugin versions 6.0.1 and earlier. The plugin reads the `oauth_callback` URL from user-submitted form data instead of validating it against a server-side stored request token, enabling callback URL manipulation. An attacker can perform an account takeover by hijacking the OAuth flow and obtaining a valid access token on behalf of a victim user. The attack requires user interaction (the victim must initiate OAuth login) but no prior authentication. A patch is available in newer versions of the plugin.
Affected products
- Jenkins Bitbucket Server Integration Plugin 6.0.1 and earlier
Timeline
- 2026-09-16: disclosed