[FortiOS] FortiGate fails to block malformed HTTP/S traffic when transparent proxy is enabled Fortinet PSIRT Advisories Fortinet PSIRT Contact: Website: https://fortiguard.fortinet.com/faq/psirt-contact FG-IR-20-172 Final 1 1 2021-01-21T00:00:00 Current version 2021-01-21T00:00:00 2021-01-21T00:00:00 When traffic other than HTTP/S (eg: SSH traffic, etc...) traverses the FortiOS on port 80/443, it is not redirected to the transparent proxy policy for processing, as it doesn't have a valid HTTP header. Improper access control Issue is observed only when the traffic is redirected to transparent proxy policy.FortiOS versions 6.4.2 and below.FortiOS versions 6.2.5 and below. Please upgrade to FortiOS version 6.4.3 or above.Workaround:To block invalid HTTP traffic on port 80, disable the tunnel-non-http setting:'''config web-proxy global set tunnel-non-http disableend '''To block invalid HTTPS traffic on port 443, set the unsupported-ssl setting to "block":'''config firewall ssl-ssh-profile edit [profile-name] config https set ports 443 set unsupported-ssl block endend''' Fortinet is pleased to thank Marko Winkler, Tobias Leydow, Marcus Schiefer and Sebastian Toth of T-Systems Multimedia Solutions GmbH for reporting this vulnerability under responsible disclosure. CVE-2020-15938 3.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N/E:U/RL:W/RC:R https://fortiguard.fortinet.com/psirt/FG-IR-20-172 [FortiOS] FortiGate fails to block malformed HTTP/S traffic when transparent proxy is enabled Reference>