CVE-2026-55193

FreeRDP 3.0.0 before 3.32.0 contains an insufficiently protected credentials vulnerability where the /restricted-admin option fails to suppress CredSSP credential delegation, sending the cleartext password to the RDP server. A compromised or man-in-the-middle destination host can decode TSPasswordCreds and the Client Info PDU to obtain reusable administrative domain, username, and password values.

The FreeRDP client 3.0.0 before 3.32.0 does not check a server-selected PROTOCOL_RDSTLS or PROTOCOL_HYBRID_EX against its enabled protocol set in nego_process_negotiation_response(), allowing a security protocol downgrade. A malicious server or man-in-the-middle can select RDSTLS to override /sec:nla pinning, complete authentication with an all-zero cookie, and receive the user's cleartext password in the Client Info PDU.

FreeRDP 3.17.1 before 3.32.0 contains a heap buffer over-read vulnerability in DynvcTrackerHandleCreateBack of the freerdp-proxy DRDYNVC channel handler that allows malicious backend RDP servers to read heap memory out of bounds. Attackers can send a CREATE_REQUEST_PDU whose channel name lacks a NUL byte, causing an unbounded snprintf read that leaks memory into proxy logs or crashes the process.

FreeRDP from 3.0.0 before 3.32.0 contains a heap out-of-bounds read vulnerability. A malicious RD Gateway can set MsgBytes far larger than the NDR string ActualCount in consent or service messages, causing UTF-8 conversion to read past the stream allocation and crash the client.

FreeRDP 3.0.0 before 3.32.0 contains an improper restriction of excessive authentication attempts in its virtual smartcard GIDS implementation, where the PIN retry counter is stored per-handle. A malicious RDP server can exhaust the counter with VERIFY APDUs, then reset attempts via a new SCardConnect, enabling unbounded online brute-forcing of the smartcard PIN.

FreeRDP from 3.0.0 before 3.32.0 contains an uninitialized memory disclosure vulnerability in smartcard_Transmit_Call. A malicious RDP server can send SCardTransmit requests with an invalid card handle and nonzero receive length, causing smartcard_pack_transmit_return to serialize up to 66,560 uninitialized heap bytes.

FreeRDP from 3.20.1 before 3.32.0 contains an uncontrolled resource allocation vulnerability. A malicious RDP server can send IRP_MJ_READ with Length 0xffffffff, causing roughly 4 GiB of zeroed allocation on 64-bit builds or an under-reserved buffer on 32-bit builds.

FreeRDP 3.11.0 before 3.32.0 does not validate that AVC444 and AVC444v2 region widths are even before YUV444 conversion, so an odd width reaches an assertion and aborts the client. A malicious or compromised RDP server can terminate a connected FreeRDP client after RDPGFX AVC444 negotiation by sending an in-bounds region rectangle with an odd width.

FreeRDP 3.0.0 before 3.32.0 contains a heap use-after-free vulnerability in smartcard emulation when SCARD_IOCTL_DISCONNECT and SCARD_IOCTL_TRANSMIT operate concurrently on one card handle. A malicious RDP server can overlap these IRPs through separate context workers to free and reuse the SCardHandle, causing client-process heap corruption and termination.

FreeRDP 3.0.0 before 3.32.0 does not remove card handles when Emulate_SCardReleaseContext releases a smartcard-emulation context, so Emulate_SCardTransmit later looks up the deleted parent context and reaches a terminating WINPR_ASSERT. A malicious RDP server can crash a connecting client with smartcard emulation and redirection enabled by releasing a context, establishing another, and issuing SCardTransmit with the stale card handle.