CVE-2026-67298
Severity CVSS v4.0:
HIGH
Type:
CWE-191
Integer Underflow (Wrap or Wraparound)
Publication date:
01/08/2026
Last modified:
03/08/2026
Description
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. For orderLength values 0..3 this causes an unsigned integer underflow to a very large size, which bypasses the Stream_EnsureRemainingCapacity() capacity check (due to pointer arithmetic wraparound) and is then passed to WTSVirtualChannelRead(), resulting in an out-of-bounds heap write. A malicious or compromised RDP client can exploit this to corrupt the heap and crash the server. Fixed in FreeRDP 3.29.0.
Impact
Base Score 4.0
8.70
Severity 4.0
HIGH
Base Score 3.x
7.50
Severity 3.x
HIGH
References to Advisories, Solutions, and Tools
- https://github.com/FreeRDP/FreeRDP/commit/46848765f2a1134f8652f8760eefb5e85d64a9b8
- https://github.com/FreeRDP/FreeRDP/commit/5370fb26fbf034ecd11d3026b6ad639b5fff493f
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmvw-52ph-q5pv
- https://www.vulncheck.com/advisories/freerdp-heap-buffer-overflow-via-rail-orderlength-underflow
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-5wr6-8m8j-3h7f