Index: cvs-1.12.13/src/client.c
===================================================================
--- cvs-1.12.13.orig/src/client.c
+++ cvs-1.12.13/src/client.c
@@ -750,6 +750,19 @@ call_in_directory (const char *pathname,
 
     assert (pathname);
 
+    /* For security reasons, if PATHNAME is absolute or attemps to ascend
+     * outside of the current sanbbox, we abort.  The server should not send us
+     * anything but relative paths which remain inside the sandbox here.
+     * Anything less means a trojan CVS server could create and edit arbitrary
+     * files on the client.
+     */
+    if (ISABSOLUTE (pathname) || pathname_levels (pathname) > 0)
+    {
+       error (0, 0,
+               "Server attempted to update a file via an invalid pathname:");
+        error (1, 0, "`%s'.", pathname);
+    }
+
     reposname = NULL;
     read_line (&reposname);
     assert (reposname);