The remote Debian host is missing a security-related update.
Multiple security issues have been found in Iceweasel, Debian's version of the Mozilla Firefox web browser: Multiple memory safety errors and buffer overflows may lead to the execution of arbitrary code or denial of service.
Upgrade the iceweasel packages. For the oldstable distribution (wheezy), these problems have been fixed in version 38.8.0esr-1~deb7u1. For the stable distribution (jessie), these problems have been fixed in version 38.8.0esr-1~deb8u1.