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CVE-2026-55639

xrdp: Out-of-bounds read in GCC Conference Create Request CS_SECURITY processing (xrdp_sec_process_mcs_data_CS_SECURITY)

5.3 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.42%Unchanged since Jul 21, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.3

xrdp: Out-of-bounds read in GCC Conference Create Request CS_SECURITY processing (xrdp_sec_process_mcs_data_CS_SECURITY)

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.

Record
CVE-2026-55639
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-125
Updated
2026-11-02
EUVDEUVD-2026-46042 5.3

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.

Record
EUVD-2026-46042
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
NVD 5.3

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.

Record
CVE-2026-55639
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-125
Updated
2026-11-02
OSV 5.3

xrdp: Out-of-bounds read in GCC Conference Create Request CS_SECURITY processing (xrdp_sec_process_mcs_data_CS_SECURITY)

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.

Record
CVE-2026-55639
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-125
Updated
2026-11-02
OSVDEBIAN-CVE-2026-55639 5.3

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.

Record
DEBIAN-CVE-2026-55639
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2026-55639 5.3

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.

Record
UBUNTU-CVE-2026-55639
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVMGASA-2026-0566 No score

Updated xrdp package fixes security vulnerabilities

lib_palette_update Heap Buffer Overflow & RCE. (CVE-2026-41252) lib_framebuffer_update Has Integer Overflow Heap Info Leak & ASLR Bypass. (CVE-2026-41521) Channel Data Forwarding Fixed-Size Buffer Overflow. (CVE-2026-44178) XRDP is vulnerable to a server timing attack, leading to user enumeration. (CVE-2026-42218) Unchecked FIPS padding length in standard RDP Security causes heap out-of-bounds read in HMAC verification. (CVE-2026-44978) Pre-auth infinite loop via totalLength=0 in TS_SHARECONTROLHEADER. (CVE-2026-54538) Malformed Confirm Active capability sets cause out-of-bounds reads. (CVE-2026-55238) No authentication required with Xvnc backend. (CVE-2026-55626) Out-of-bounds read in GCC Conference Create Request CS_SECURITY processing (xrdp_sec_process_mcs_data_CS_SECURITY). (CVE-2026-55639) Out-of-bounds read in Client Control PDU processing (xrdp_rdp_process_data_control). (CVE-2026-55645)

Record
MGASA-2026-0566
Updated
2026-11-02
OSVopenSUSE-SU-2026:11543-1 No score

xrdp-0.10.6.1-1.1 on GA media

These are all security issues fixed in the xrdp-0.10.6.1-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11543-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
xrdp
Debian:12
before 0.9.21.1-1+deb12u3, plus listed versions
0.9.21.1-10.9.21.1-1+deb12u10.9.21.1-1+deb12u2
0.9.21.1-1+deb12u3
xrdp
Debian:13
before 0.10.1-3.1+deb13u2, plus listed versions
0.10.1-3.10.10.1-3.1+deb13u1
0.10.1-3.1+deb13u2
xrdp
Debian:14
before 0.10.6.1-2, plus listed versions
0.10.1-3.10.10.1-40.10.1-4.10.10.2-10.10.2-2
Show 14 moreShow less
0.10.4.1-10.10.4.1-20.10.5-10.10.5-20.10.5-30.10.5-40.10.5-50.10.6-10.10.6-20.10.6-30.10.6-40.10.6-50.10.6.1-10.10.6.1-2~bpo13+1
0.10.6.1-2
xrdp
Mageia:10
From an advisory covering 10 CVEs
before 0.10.6.1-2.mga10
0.10.6.1-2.mga10
xrdp
Ubuntu:Pro:14.04:LTS
All versions, plus listed versions
0.6.0-10.6.0-1ubuntu0.10.6.0-1ubuntu0.1+esm10.6.0-1ubuntu0.1+esm20.6.0-1ubuntu0.1+esm3
None known
xrdp
Ubuntu:Pro:16.04:LTS
All versions, plus listed versions
0.6.1-20.6.1-2ubuntu0.10.6.1-2ubuntu0.30.6.1-2ubuntu0.3+esm10.6.1-2ubuntu0.3+esm20.6.1-2ubuntu0.3+esm3
None known
xrdp
Ubuntu:Pro:18.04:LTS
All versions, plus listed versions
0.9.1-90.9.4-10.9.4-20.9.4-30.9.4-4
Show 7 moreShow less
0.9.4-50.9.5-10.9.5-1build10.9.5-20.9.5-2ubuntu0.1~esm10.9.5-2ubuntu0.1~esm20.9.5-2ubuntu0.1~esm3
None known
xrdp
Ubuntu:Pro:20.04:LTS
All versions, plus listed versions
0.9.9-10.9.12-10.9.12-1ubuntu0.10.9.12-1ubuntu0.1+esm10.9.12-1ubuntu0.1+esm2
None known
xrdp
Ubuntu:22.04:LTS
All versions, plus listed versions
0.9.15-1ubuntu10.9.17-10.9.17-20.9.17-2ubuntu10.9.17-2ubuntu2
Show 5 moreShow less
0.9.17-2ubuntu2+esm10.9.17-2ubuntu30.9.17-2ubuntu3+esm10.9.17-2ubuntu3+esm20.9.17-2ubuntu3.1
None known
xrdp
Ubuntu:24.04:LTS
All versions, plus listed versions
0.9.21.1-10.9.24-20.9.24-30.9.24-3build10.9.24-3build20.9.24-40.9.24-4ubuntu0.1~esm10.9.24-4ubuntu0.1
None known
Show 4 moreShow less
Affected packages
PackageAffectedFixed
xrdp
Ubuntu:25.10
All versions, plus listed versions
0.10.1-30.10.1-3.10.10.1-3.1+deb13u1build0.25.10.1
None known
xrdp
Ubuntu:26.10
All versions, plus listed versions
0.10.1-4.10.10.6.1-2ubuntu1
None known
xrdp
Ubuntu:26.04:LTS
All versions, plus listed versions
0.10.1-3.10.10.1-40.10.1-4.10.10.1-4.1ubuntu0.1
None known
xrdp
openSUSE:Tumbleweed
From an advisory covering 10 CVEs
before 0.10.6.1-1.1
0.10.6.1-1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-55639 is a medium vulnerability (CVSS 5.3) in Neutrinolabs Xrdp, published July 20, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.42%, the 36th percentile. Fixed in xrdp 0.9.21.1-1+deb12u3.

References

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