RustDesk versions before 1.4.7 contain an uncontrolled speculative memory allocation vulnerability in BytesCodec. Before authentication, the decoder trusts the payload length encoded in a four-byte frame header and reserves that amount before receiving the payload. A crafted header can request up to 1,073,741,823 bytes of capacity, allowing unauthenticated attackers to use concurrent TCP connections to cause memory exhaustion and denial of service. The fix caps header-triggered speculative preallocation at 256 KiB.
https://www.vulncheck.com/advisories/rustdesk-uncontrolled-memory-allocation-dos-via-bytescodec
https://github.com/rustdesk/rustdesk/releases/tag/1.4.7
https://github.com/rustdesk/rustdesk/commit/518296f2570d107ad416f29ade5fcce3177f4115
https://github.com/rustdesk/hbb_common/commit/547da54b4ee58eed47163fbd47edb4639e3d88de
Published: 2026-08-26
Updated: 2026-08-28
Base Score: 7.8
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C
Severity: High
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity: High
Base Score: 8.7
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00528