Guillaume Teissier is a French security researcher working for Orange Group. His main activities are penetration tests and audits on Telco infrastructure and services. He has found several vulnerabilities, which have been responsibly disclosed, on various products, like CVE-2018-7364 (ZTE IN), CVE-2017-10617 (Juniper Contrail), or CVE-2016-6271 (bzrtp). He has given talks at SSTIC 2018 and Troopers TSD 2019.