Privilege escalation through link refactoring

When links are modified as part of a refactoring (e.g. a page rename) the document is saved using current author as metadata author. This might lead to privilege escalation and script right execution.

Reproduction steps:

• Create 2 users Foo without script right and Bar with script right
• Login with Foo
• Create a page P1
• Create a page P2 with a MovieClass xobject
• In the "poster" field of the xobject put a link to P1 and a velocity script
• Login with Bar and rename P1 to P3

Expected result:

• P2 gets a new version and its link is refactored, the history shows that Bar performed the refactoring, but the velocity script remain not executed

Obtained result:

• P2 gets a new version and its link is refactored, the history shows that Bar performed the refactoring, but the velocity script is executed