Upgrade Commons FileUpload from 1.3.1-jenkins-2 to 1.4

Background

See jenkinsci/jenkins#5174. Subsumes jenkinsci/jenkins#5171. See also the corresponding mailing list thread.

Problem

Jenkins core uses a fork of Commons FileUpload 1.3.1 (which was released upstream on February 7, 2014). Two changes were made to the Jenkins fork:

1. DiskFileItem was made no longer Serializable in commit 28d997704f as part of SECURITY-159 on September 27, 2014. Upstream made the same change over 4 years later in 1.4 (which was released on December 23, 2018).
2. The fix for CVE-2016-3092 (originally released upstream in 1.3.2 on May 26, 2016) was backported to the Jenkins fork in commit ea981a029c as part of SECURITY-490 on September 28-29, 2017.

Solution

As of 2021, the latest upstream release (1.4) contains all the changes present in the fork; therefore, the fork is no longer necessary. Furthermore, it prevents us from receiving upstream fixes.

Solution

Upgrade to the latest upstream release, Commons FileUpload 1.4.