A newly disclosed Jenkins vulnerability, tracked as CVE-2026-53435, is now being actively exploited in the wild. The flaw allows an authenticated attacker with relatively low privileges to POST a malicious config.xml file, abuse Jenkins’ deserialization handling, and route requests through Stapler to access sensitive files on the Jenkins controller.

The issue affects Jenkins weekly versions up to 2.567 and LTS versions up to 2.555.2. Successful exploitation can lead to arbitrary file read, user impersonation, Script Console access, and possible exposure of SSH keys, credentials, and internal Jenkins secrets. Administrators are urged to upgrade immediately to Jenkins weekly 2.568 or LTS 2.555.3, review logs for suspicious createView requests, and audit users with View/Configure, Item/Configure, or Agent/Configure permissions.