High [CVE-2026-55194] Heap-buffer-overflow allows arbitrary code execution via crafted RPC response
This high-severity Red Hat Linux advisory covers CVE-2026-55194 affecting Red Hat Enterprise Linux 10, Red Hat package: freerdp.
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Summary
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, rpc_client_recv_fragment in libfreerdp/core/gateway/rpc_client.c ensures the response reassembly stream capacity using only the server-declared alloc_hint rather than the actual StubLength about to be written.
A malicious TS Gateway can send a PTYPE_RESPONSE with a small alloc_hint and a much larger frag_length, causing Stream_Write to copy attacker-controlled stub data beyond the 4096-byte pdu->s buffer. This can crash the client and may permit code execution through heap corruption.
This issue is fixed in version 3.27.0. A flaw was found in FreeRDP.
A remote attacker, specifically a malicious TS Gateway, can exploit a heap-buffer-overflow vulnerability by sending a specially crafted Remote Desktop Protocol (RDP) response. This occurs because the client incorrectly uses a smaller `alloc_hint` value instead of the actual `StubLength` for buffer capacity during response reassembly.
This allows attacker-controlled data to be written beyond the intended buffer, leading to a client crash and potentially enabling arbitrary code execution. This can result in client crashes or potential arbitrary code execution.
Red Hat severity: Important — CVSS 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). Weakness: CWE-120.
Affected Red Hat products: Red Hat Enterprise Linux 10.
- < 3.27.0
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation checklist
- To mitigate this vulnerability, avoid connecting through untrusted TS Gateways (RD Gateways) or disable gateway parameters (such as omitting `/g:` in `xfreerdp`) to force direct RDP connections and bypass RPC response parsing.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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