Improper Input Validation
A maliciously constructed svn+ssh:// URL would cause Subversion clients before 1.8.19, 1.9.x before 1.9.7, and 1.10.0.x through 1.10.0-alpha3 to run an arbitrary shell command. Such a URL could be generated by a malicious server, by a malicious user committing to a honest server (to attack another user of that server's repositories), or by a proxy server. The vulnerability affects all clients, including those that use file://, http://, and plain (untunneled) svn://.
CWE-20 - Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.