CVE-2026-30796

Cleartext Transmission of Sensitive Information, Insufficiently Protected Credentials vulnerability in rustdesk-client RustDesk Client rustdesk-client on Windows, MacOS, Linux, iOS, Android (Address book sync, Heartbeat sync loop modules) allows Sniffing Attacks. The client places the preset address-book password verbatim into the heartbeat sync JSON body (src/hbbs_http/sync.rs). Over an intact HTTPS session it is not exposed in transit, but it is a reusable shared secret rather than a zero-knowledge proof, so it is recovered by any party that becomes the API endpoint - under the automatic invalid-certificate TLS downgrade (CVE-2026-30794) or a re-homed/rogue API server (CVE-2026-30797) - and the leaked credential then authorizes the server-side address book. This vulnerability is associated with program files src/hbbs_http/sync.rs and program routines heartbeat sync body builder (emits preset-address-book-password). This issue affects RustDesk Client: through 1.4.8.

• https://docs.google.com/document/d/e/2PACX-1vSds6jjpd38oO_yIAyd1HYtKNUuea-I-ozAPpGhYI7QgAU-QGJ7D8a4rOZVj1vmiUXV1EcdRHf9aZAW/pub
• https://rustdesk.com/docs/en/
• https://www.vulsec.org/