# CVE-2026-55639: neutrinolabs xrdp out-of-bounds read in MCS data processing

Source: https://junglewise.ai/threats/cve-2026-55639-neutrinolabs-xrdp-out-of-bounds-read-in-mcs-data-processing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-20. Updated: 2026-07-20  
License: CC BY 4.0 with a link back

CVE-2026-55639 · Severity: medium · CVSS 5.3 · Published 2026-07-20

xrdp is an open-source tool that allows users to remotely control a computer's desktop over a network. A security flaw has been found where the software does not properly check the size of incoming connection requests. This could allow an unauthorized person to peek at small amounts of the computer's memory, potentially revealing sensitive information that could be used in further attacks.

Technologies: [Neutrinolabs Xrdp](https://junglewise.ai/threats/technologies/xrdp). Vendors: [Neutrinolabs](https://junglewise.ai/threats/vendors/neutrinolabs).

## Quick answers

**Is CVE-2026-55639 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55639 being exploited in the wild.

**How severe is CVE-2026-55639?** Medium severity, with a CVSS score of 5.3, published 20 July 2026.

**Which products and versions are affected?** Neutrinolabs Xrdp <= 0.10.6.

**Is there a fix for CVE-2026-55639?** A patch was published on 2026-07-06: Version 0.10.6.1 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55639 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-55639?** Check whether you run Neutrinolabs Xrdp at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds read vulnerability (CWE-125) exists in xrdp versions 0.10.6 and prior during the parsing of Client Security Data within the Client MCS Connect Initial PDU. The flaw occurs because the parser fails to perform sufficient length validation on incoming data blocks during the initial capability and security negotiation phase. A remote, unauthenticated attacker can exploit this by sending a specially crafted RDP packet. This missing bounds check allows the process to read a small number of bytes beyond the intended buffer, potentially leaking sensitive process memory. The issue is addressed in version 0.10.6.1.

## Affected products

- neutrinolabs xrdp <= 0.10.6

## Timeline

- 2026-07-02: advisory: GitHub Security Advisory published by maintainers
- 2026-07-06: patched: Version 0.10.6.1 released
- 2026-07-20: disclosed: CVE published to NVD

## References

- [https://github.com/neutrinolabs/xrdp/releases/tag/v0.10.6.1](https://github.com/neutrinolabs/xrdp/releases/tag/v0.10.6.1)
- [https://github.com/neutrinolabs/xrdp/security/advisories/GHSA-6g36-mxcf-r3gc](https://github.com/neutrinolabs/xrdp/security/advisories/GHSA-6g36-mxcf-r3gc)

## Related threats

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- [neutrinolabs xrdp out-of-bounds read in Client Control PDU processing](https://junglewise.ai/threats/cve-2026-55645-neutrinolabs-xrdp-out-of-bounds-read-in-client-control-pdu)
- [neutrinolabs xrdp buffer over-read in RDP Confirm Active PDU](https://junglewise.ai/threats/cve-2026-55238-neutrinolabs-xrdp-buffer-over-read-in-rdp-confirm-active-pdu)
- [neutrinolabs xrdp infinite loop denial of service](https://junglewise.ai/threats/cve-2026-54538-neutrinolabs-xrdp-infinite-loop-denial-of-service)
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