Versions mentioned in the description apply to the upstream
Remediation section below for
Debian:9 relevant versions.
Subversion's mod_authz_svn module will crash if the server is using in-repository authz rules with the AuthzSVNReposRelativeAccessFile option and a client sends a request for a non-existing repository URL. This can lead to disruption for users of the service. This issue was fixed in mod_dav_svn+mod_authz_svn servers 1.14.1 and mod_dav_svn+mod_authz_svn servers 1.10.7
subversion to version 1.9.5-1+deb9u6 or higher.