CVE-2026-55639
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.
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
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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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
| Package | Affected | Fixed |
|---|---|---|
xrdpDebian: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 |
xrdpDebian: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 |
xrdpDebian: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 less0.10.4.1-10.10.4.1-20.10.5-10.10.5-20.10.5-30.10.5-40.10.5-50.10.6-10.10.6-20.10.6-30.10.6-40.10.6-50.10.6.1-10.10.6.1-2~bpo13+1 |
0.10.6.1-2 |
xrdpMageia:10 From an advisory covering 10 CVEs |
before 0.10.6.1-2.mga10 | 0.10.6.1-2.mga10 |
xrdpUbuntu: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 |
xrdpUbuntu: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 |
xrdpUbuntu: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 less0.9.4-50.9.5-10.9.5-1build10.9.5-20.9.5-2ubuntu0.1~esm10.9.5-2ubuntu0.1~esm20.9.5-2ubuntu0.1~esm3 |
None known |
xrdpUbuntu: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 |
xrdpUbuntu: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 less0.9.17-2ubuntu2+esm10.9.17-2ubuntu30.9.17-2ubuntu3+esm10.9.17-2ubuntu3+esm20.9.17-2ubuntu3.1 |
None known |
xrdpUbuntu: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
| Package | Affected | Fixed |
|---|---|---|
xrdpUbuntu: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 |
xrdpUbuntu:26.10 |
All versions, plus listed versions 0.10.1-4.10.10.6.1-2ubuntu1 |
None known |
xrdpUbuntu: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 |
xrdpopenSUSE:Tumbleweed From an advisory covering 10 CVEs |
before 0.10.6.1-1.1 | 0.10.6.1-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE 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
github.com/neutrinolabs/xrdp/security/advisories/GHSA-6g36-mxcf-r3gc
github.com/neutrinolabs/xrdp/releases/tag/v0.10.6.1
github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55639.json
nvd.nist.gov/vuln/detail/CVE-2026-55639
security-tracker.debian.org/tracker/CVE-2026-55639
advisories.mageia.org/MGASA-2026-0566.html
Show 16 moreShow less
bugs.mageia.org/show_bug.cgi?id=35945
lists.fedoraproject.org/archives/list/[email protected]/message/5ZQ6QE47Z3SMILAAOHQ2RKDQFJOK2M4X
lists.fedoraproject.org/archives/list/[email protected]/message/JWYOEVBA3574FXNPXKDS3FPNCQ3SDAOM
lists.debian.org/debian-security-announce/2026/msg00380.html
ubuntu.com/security/CVE-2026-55639
cve.org/CVERecord?id=CVE-2026-55639
suse.com/security/cve/CVE-2026-41252
suse.com/security/cve/CVE-2026-41521
suse.com/security/cve/CVE-2026-42218
suse.com/security/cve/CVE-2026-44178
suse.com/security/cve/CVE-2026-44978
suse.com/security/cve/CVE-2026-54538
suse.com/security/cve/CVE-2026-55238
suse.com/security/cve/CVE-2026-55626
suse.com/security/cve/CVE-2026-55639
suse.com/security/cve/CVE-2026-55645