CVE-2026-63096: Matrix-Org Dendrite

Medium severity, CVSS 5.8. EPSS: 0.3% chance of exploitation in the next 30 days.

Dendrite through 0.13.8 contains a server-side request forgery vulnerability that allows unauthenticated attackers to cause the server to open outbound TLS connections to arbitrary hosts and ports by supplying an unvalidated serverName parameter to the legacy media download endpoint. Attackers can exploit distinguishable error response classes and leaked internal IP addresses in error messages to perform blind port scanning and enumerate internal network topology.

Affected products

• Matrix-Org Dendrite: up to and including 0.13.8

Published 2026-07-17. Last modified 2026-07-17.