CVE-2026-55639

MEDIUMCVSS 5.3/10EPSS 0.25%

Last modified

CVE-2026-55639 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. xrdp is an open source RDP server. Versions 0.10.6 and prior contain a vulnerability concerning the parsing of Client Security Data within the Client MCS Connect Initial PDU with GCC Conference Create Request during the connection sequence. EPSS estimates a 0.25% chance of exploitation in the next 30 days.

Description

xrdp is an open source RDP server. Versions 0.10.6 and prior contain a vulnerability concerning the parsing of Client Security Data within the Client MCS Connect Initial PDU with GCC Conference Create Request during the connection sequence. During the initial capability and security negotiation phase, the parser fails to perform sufficient length validation for the incoming data block. A remote, unauthenticated attacker could potentially exploit this flaw by sending a specially crafted RDP packet containing malformed data. Due to missing bounds checks, the xrdp process may read a small number of bytes beyond the declared data block boundary, potentially disclosing process memory contents that could be combined with other vulnerabilities. This issue has been fixed in version 0.10.6.1.

Metrics

CVSS 3.1
5.3/10

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

EPSS Probability
0.25%

16.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
NeutrinolabsXrdp< 0.10.6.1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-55639?
xrdp is an open source RDP server. Versions 0.10.6 and prior contain a vulnerability concerning the parsing of Client Security Data within the Client MCS Connect Initial PDU with GCC Conference Create Request during the connection sequence. During the initial capability and security negotiation phase, the parser fails to perform sufficient length validation for the incoming data block. A remote, unauthenticated attacker could potentially exploit this flaw by sending a specially crafted RDP packet containing malformed data. Due to missing bounds checks, the xrdp process may read a small number of bytes beyond the declared data block boundary, potentially disclosing process memory contents that could be combined with other vulnerabilities. This issue has been fixed in version 0.10.6.1.
How severe is CVE-2026-55639?
CVE-2026-55639 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.
How do I fix CVE-2026-55639?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST