I checked the failed unit tests, and they're unrelated to this patch. It looks like branch-2.6 precommit and test suite is pretty broken.
I applied the patch and poked around. Looks like we get double escaping on the logLevel endpoint:
Submitted Log Name: <>'";
Log Class: org.apache.commons.logging.impl.Log4JLogger
Submitted Level: <>"';
Bad Level : <>"';
Effective level: INFO
I also tried browseDirectory.jsp with a directory named "<>" and "abc" and it seems to be escaping the entire link:
Didn't check the others, but I think we need to do manual verification of these to make sure they're escaping correctly.