CVE-2026-55238: xrdp: Malformed Confirm Active capability sets cause out-of-bounds reads

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-20 · updated 2026-10-24
Weakness: CWE-126

Description

xrdp is an open source RDP server. Versions 0.10.6 and prior contain a vulnerability concerning the processing of RDP Confirm Active PDU, where during the capability negotiation phase, the parser did not perform sufficient length validation for specific capability sets. A remote, unauthenticated attacker could potentially exploit this flaw by sending a specially crafted RDP packet containing malformed capability data. Due to missing bounds checks, the xrdp process may perform out-of-bounds memory reads, which can result in the termination of the service (Denial of Service). 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.

Affected products

neutrinolabs xrdp: before 0.10.6.1 — fixed in 0.10.6.1

How to fix

Upgrade to a fixed version: neutrinolabs xrdp 0.10.6.1. Check the vendor advisory for mitigations.

References

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