xrdp is an open source RDP server. Versions 0.10.6 and prior contain a heap out-of-bounds read vulnerability within the FIPS-specific receive paths. This vulnerability does not affect the default configuration of xrdp. The vulnerability is only exploitable when the security layer is set to securitylayer=negotiate or securitylayer=rdp, and the crypto level is changed to cryptlevel=fips in xrdp.ini. In this specific non-default mode, the server fails to validate the FIPS padding length field, leading to a pointer underflow and a subsequent negative length calculation. An unauthenticated remote attacker can exploit this by sending a crafted FIPS-protected PDU, causing a heap out-of-bounds read that results in a process crash and denial of service (DoS). However, since xrdp forks a new process for each connection by default, an out-of-bounds read causing a process crash is unlikely to bring down the entire xrdp service. This issue has been fixed in version 0.10.6.1.

xrdp is an open source RDP server. Versions 0.10.6 and prior contain a timing side-channel vulnerability in the login interface. Due to a discrepancy in response processing times, a remote attacker can infer the existence of a username on the system, leading to unauthorized information disclosure via username enumeration. This issue has been fixed in version 0.10.6.1.

Buffer overflow in the xrdpbitmapinvalidate function in xrdp/xrdpbitmap.c in xrdp 0.4.1 and earlier allows remote attackers to execute arbitrary code via a crafted request.

The rdprdpprocesscolorpointerpdu function in rdp/rdprdp.c in xrdp 0.4.1 and earlier allows remote RDP servers to have an unknown impact via input data that sets crafted values for certain length variables, leading to a buffer overflow.

Array index error in the xrdpbitmapdefproc function in xrdp/funcs.c in xrdp 0.4.1 and earlier allows remote attackers to execute arbitrary code via vectors that manipulate the value of the editpos structure member.

xrdp is an open source RDP server. In versions through 0.10.5, xrdp does not implement verification for the Message Authentication Code (MAC) signature of encrypted RDP packets when using the "Classic RDP Security" layer. While the sender correctly generates signatures, the receiving logic lacks the necessary implementation to validate the 8-byte integrity signature, causing it to be silently ignored. An unauthenticated attacker with man-in-the-middle (MITM) capabilities can exploit this missing check to modify encrypted traffic in transit without detection. It does not affect connections where the TLS security layer is enforced. This issue has been fixed in version 0.10.6. If users are unable to immediately upgrade, they should configure xrdp.ini to enforce TLS security (securitylayer=tls) to ensure end-to-end integrity.

xrdp is an open source RDP server. In versions through 0.10.5, the session execution component did not properly handle an error during the privilege drop process. This improper privilege management could allow an authenticated local attacker to escalate privileges to root and execute arbitrary code on the system. An additional exploit would be needed to facilitate this. This issue has been fixed in version 0.10.6.

xrdp is an open source RDP server. Versions through 0.10.5 contain a heap-based buffer overflow vulnerability in the NeutrinoRDP module. When proxying RDP sessions from xrdp to another server, the module fails to properly validate the size of reassembled fragmented virtual channel data against its allocated memory buffer. A malicious downstream RDP server (or an attacker capable of performing a Man-in-the-Middle attack) could exploit this flaw to cause memory corruption, potentially leading to a Denial of Service (DoS) or Remote Code Execution (RCE). The NeutrinoRDP module is not built by default. This vulnerability only affects environments where the module has been explicitly compiled and enabled. Users can verify if the module is built by checking for --enable-neutrinordp in the output of the xrdp -v command. This issue has been fixed in version 0.10.6.

xrdp is an open source RDP server. Versions through 0.10.5 contain a heap-based buffer overflow vulnerability in its logon processing. In environments where domainuserseparator is configured in xrdp.ini, an unauthenticated remote attacker can send a crafted, excessively long username and domain name to overflow the internal buffer. This can corrupt adjacent memory regions, potentially leading to a Denial of Service (DoS) or unexpected behavior. The domainnameseparator directive is commented out by default, systems are not affected by this vulnerability unless it is intentionally configured. This issue has been fixed in version 0.10.6.

xrdp is an open source RDP server. Versions through 0.10.5 contain an out-of-bounds read vulnerability during the RDP capability exchange phase. The issue occurs when memory is accessed before validating the remaining buffer length. A remote, unauthenticated attacker can trigger this vulnerability by sending a specially crafted Confirm Active PDU. Successful exploitation could lead to a denial of service (process crash) or potential disclosure of sensitive information from the process memory. This issue has been fixed in version 0.10.6.

xrdp is an open source RDP server. Versions through 0.10.5 have a heap-based buffer overflow in the EGFX (graphics dynamic virtual channel) implementation due to insufficient validation of client-controlled size parameters, allowing an out-of-bounds write via crafted PDUs. Pre-authentication exploitation can crash the process, while post-authentication exploitation may achieve remote code execution. This issue has been fixed in version 0.10.6. If users are unable to immediately update, they should run xrdp as a non-privileged user (default since 0.10.2) to limit the impact of successful exploitation.

xrdp is an open source RDP server. Versions through 0.10.5 have an out-of-bounds read vulnerability in the pre-authentication RDP message parsing logic. A remote, unauthenticated attacker can trigger this flaw by sending a specially crafted sequence of packets during the initial connection phase. This vulnerability results from insufficient validation of input buffer lengths before processing dynamic channel communication. Successful exploitation can lead to a denial-of-service (DoS) condition via a process crash or potential disclosure of sensitive information from the service's memory space. This issue has been fixed in version 0.10.6.

xrdp is an open source RDP server. Versions through 0.10.5 allow an authenticated remote user to execute arbitrary commands on the server due to unsafe handling of the AlternateShell parameter in xrdp-sesman. When the AllowAlternateShell setting is enabled (which is the default when not explicitly configured), xrdp accepts a client-supplied AlternateShell value and executes it via /bin/sh -c during session initialization. This results in shell-interpreted execution of unsanitized, user-controlled input. This behavior effectively provides a scriptable remote command execution primitive over RDP within the security context of the authenticated user, occurring prior to normal window manager startup. This can bypass expected session initialization flows and operational assumptions that restrict execution to interactive desktop environments. This issue has been fixed in version 0.10.6.