GHSA-9x82-rm84-c6x7: DSpace has possible Remote Code Execution (RCE) through Velocity Templates used by LDN

Overview Remote Code Execution (RCE) is possible via Velocity Templates used by DSpace for COAR Notify/LDN messages. _This vulnerability impacts DSpace versions 8.0 <= 8.3, 9.0 <= 9.2._ The attacker MUST already have DSpace administrator credentials in order to perform the attack. This attack is related to the path traversal attack identified in GHSA-9qm4-rh6w-pq5x as it was the impactful part of the "proof-of-concept" attack chain. Impact When chained with the LDN Path Traversal Attack identified in GHSA-9qm4-rh6w-pq5x, it may be possible to execute Java directly from Velocity templates using reflection. This is a very high impact vulnerability, but the attack can only be performed by a user that has DSpace Administrator privileges. Disabling LDN (see below) removes all known attack paths. Velocity is also used for email templating, but there is no known attack path via emails templates. Nonetheless, the patches below also apply to email templates. Patches The fix is included in DSpace 8.4, 9.3 and 10.0. Please upgrade to one of these versions or disable LDN (see below) If users cannot upgrade immediately, it is possible to manually patch their DSpace backend. (No changes are necessary to the frontend.) A pull request exists which can be used to patch systems running DSpace 8.x or 9.x. - Pull request for 9.x: https://github.com/DSpace/DSpace/pull/12548 (Downloadable patch file) - Pull request for 8.x: https://github.com/DSpace/DSpace/pull/12549 (Downloadable patch file) Apply the patch to a DSpace instance If at all possible, DSpace project maintainers recommend disabling LDN (see below) or upgrading a DSpace site based on the upgrade instructions. However, if users are unable to do so, they can manually apply the above patches to their Space backend as follows: 1. Download the appropriate patch file to the machine where DSpace backend is running 2. From the [dspace-src] folder, apply the patch, e.g. git apply [name-of-file].patch 3. Now, update the applic