Server-Side Request Forgery (SSRF) on redirects and federation in Matrix Media Repo
Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix. Matrix Media Repo (MMR) is vulnerable to server-side request forgery, serving content from a private network it can access, under certain conditions. This is fixed in MMR v1.3.8. Users are advised to upgrade. Restricting which hosts MMR is allowed to contact via (local) firewall rules or a transparent proxy and may provide a workaround for users unable to upgrade.