CVE-2026-33516

CriticalUpdated

Published: 17 April 2026

Published

17 April 2026

Modified

27 April 2026

KEV Added

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Patch

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CVSS Score 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

EPSS Score 0.0012 29.9th percentile

Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-33516 is a critical-severity Out-of-bounds Read (CWE-125) vulnerability in Neutrinolabs Xrdp. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 29.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-16 (Memory Protection).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 2 other techniques. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Mandates timely patching of xrdp to version 0.10.6 or later to remediate the out-of-bounds read vulnerability during RDP capability exchange.

SI-10 Information Input Validation good match

prevent

Requires validation of incoming RDP Confirm Active PDU buffer lengths to prevent out-of-bounds memory access by remote attackers.

SI-16 Memory Protection good match

prevent

Implements memory protections such as ASLR and guard pages to mitigate denial-of-service crashes and sensitive information disclosure from out-of-bounds reads in xrdp.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1499.004 Application or System Exploitation Impact

Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.

attack.mitre.org →

Why these techniques?

Remote unauthenticated exploitation of a public-facing RDP server (xrdp) via crafted PDU enables initial access or lateral movement exploitation techniques (T1190, T1210) and application DoS via crash (T1499.004); potential memory disclosure aligns with exploitation impacts.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

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.

Deeper analysisAI

CVE-2026-33516 is an out-of-bounds read vulnerability (CWE-125) affecting xrdp, an open source Remote Desktop Protocol (RDP) server. The flaw exists in versions through 0.10.5 and occurs during the RDP capability exchange phase, where memory is accessed prior to validating the remaining buffer length. This high-severity issue, scored at CVSS 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H), was published on 2026-04-17.

A remote, unauthenticated attacker can exploit this vulnerability by sending a specially crafted Confirm Active PDU to an affected xrdp instance. Successful exploitation may result in a denial of service via process crash or potential disclosure of sensitive information from the server's process memory, depending on the memory layout and contents at the time of the out-of-bounds access.

The xrdp project has addressed this vulnerability in version 0.10.6, as detailed in the release notes at https://github.com/neutrinolabs/xrdp/releases/tag/v0.10.6 and the security advisory at https://github.com/neutrinolabs/xrdp/security/advisories/GHSA-rvh9-9wm3-28c7. Security practitioners should upgrade to 0.10.6 or later and consider network segmentation or firewalls to restrict RDP traffic until patching is complete.