OpenNMS vulnerabilities

OpenNMS has a default password of 'rtc' for the rtc account, which makes it easier for remote attackers to obtain access by leveraging knowledge of the credentials.

OpenNMS Meridian and Horizon XML parsing lacked an effective limit on entity expansion, allowing server memory exhaustion. An authenticated user with provisioning access can supply a document with a DOCTYPE and internal entities via requisition or foreign-source import, causing a denial of service.

An incorrect authorization check in the v2 Alarm REST API in OpenNMS Meridian and Horizon allows a low-privileged authenticated user (ROLE_REST) to acknowledge, escalate, or clear alarms recorded as an arbitrary username, and, when also assigned ROLE_READONLY, to modify alarm state despite the read-only restriction. A credential check is guarded by an inverted condition, so it never executes for a real (non-blank) username.

A JEXL expression sandbox bypass exists in multiple versions of OpenNMS Meridian and Horizon. A low-privileged authenticated user can submit a crafted expression to the Measurements REST API that escapes the sandbox and loads arbitrary Java classes on the server. This can potentially allow an attacker to gain access to confidential information and compromise integrity.