The issue affects Proxmox Virtual Environment (PVE) and Proxmox Mail Gateway (PMG) when proxying HTTP requests between pve(pmg)proxy and pve(pmg)daemon, allowing an attacker with an unprivileged account to craft an HTTP request and achieve Server-Side Request Forgery (SSRF) and file disclosure of any files on the server. Additionally, in Proxmox Mail Gateway, privilege escalation to the root@pam account is possible if the backup feature has been used, due to backup files having 0644 permissions and containing an authkey value.