CVE-2026-67298 FreeRDP CVE debrief

Who should care

Users of FreeRDP versions 3.28.0 and earlier, administrators of systems with RDP access, and security teams responsible for vulnerability management should be aware of this vulnerability. Affected systems may be exposed to potential exploitation, and defenders should review and implement mitigations to prevent exploitation. This includes verifying FreeRDP version, monitoring for suspicious RDP activity, and implementing compensating controls for RDP access.

Technical summary

FreeRDP versions 3.28.0 and earlier contain a heap buffer overflow in the server-side RAIL channel handler (rail_server_handle_messages() in channels/rail/server/rail_main.c). When processing a RAIL PDU header, the code subtracts RAIL_PDU_HEADER_LENGTH from the peer-controlled orderLength field without first verifying orderLength is at least the header length. This can lead to an unsigned integer underflow, bypassing the Stream_EnsureRemainingCapacity() capacity check and resulting in an out-of-bounds heap write. The vulnerability is fixed in FreeRDP 3.29.0.

Defensive priority

FreeRDP heap buffer overflow via RAIL orderLength underflow

Recommended defensive actions

• Inventory and verify FreeRDP version
• Apply FreeRDP 3.29.0 or later
• Monitor for suspicious RDP activity
• Implement compensating controls for RDP access
• Review system logs for exposure
• Track exceptions and retest remediated assets
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

FreeRDP versions 3.28.0 and earlier contain a heap buffer overflow in the server-side RAIL channel handler. A malicious or compromised RDP client can exploit this to corrupt the heap and crash the server. Evidence is limited to public sources and may not reflect the full scope of affected systems or potential impact. Defenders should verify FreeRDP version, review system logs for suspicious activity, and implement compensating controls for RDP access.

Official resources