Description
It was discovered that libXdmcp before 1.1.2 including used weak entropy to generate session keys. On a multi-user system using xdmcp, a local attacker could potentially use information available from the process list to brute force the key, allowing them to hijack other users' sessions.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Xorg | libXdmcp | 1.1.2 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libxdmcp | 1:1.1.2-2 | — |
| Debian 13 | libxdmcp | 1:1.1.2-2 | — |
| Debian 12 | libxdmcp | 1:1.1.2-2 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libxdmcp | 1:1.1.2-3 | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | libxdmcp | 1:1.1.2-1.1ubuntu0.1~esm1 | USN-5690-1 |
| Ubuntu Pro 14.04 LTS | libxdmcp | 1:1.1.1-1ubuntu0.1~esm1 | USN-5690-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | libICE +1 | 1.0.9-9.el7 | RHSA-2017:1865 |
| RHEL 7 | libX11 +2 | 1.6.5-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXaw +1 | 1.0.13-4.el7 | RHSA-2017:1865 |
| RHEL 7 | libXcursor +1 | 1.1.14-8.el7 | RHSA-2017:1865 |
| RHEL 7 | libXdmcp +1 | 1.1.2-6.el7 | RHSA-2017:1865 |
| RHEL 7 | libXfixes +1 | 5.0.3-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXfont +1 | 1.5.2-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXfont2 +1 | 2.0.1-2.el7 | RHSA-2017:1865 |
| RHEL 7 | libXi +1 | 1.7.9-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXpm +1 | 3.5.12-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXrandr +1 | 1.5.1-2.el7 | RHSA-2017:1865 |
| RHEL 7 | libXrender +1 | 0.9.10-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXt +1 | 1.1.5-3.el7 | RHSA-2017:1865 |
| RHEL 7 | libXtst +1 | 1.2.3-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXv +1 | 1.0.11-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXvMC +1 | 1.0.10-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libXxf86vm +1 | 1.1.4-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libdrm +2 | 2.4.74-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libepoxy +1 | 1.3.1-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libevdev +2 | 1.5.6-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libfontenc +1 | 1.1.3-3.el7 | RHSA-2017:1865 |
| RHEL 7 | libinput +1 | 1.6.3-2.el7 | RHSA-2017:1865 |
| RHEL 7 | libvdpau +2 | 1.1.1-3.el7 | RHSA-2017:1865 |
| RHEL 7 | libwacom +2 | 0.24-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libxcb +2 | 1.12-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libxkbcommon +3 | 0.7.1-1.el7 | RHSA-2017:1865 |
| RHEL 7 | libxkbfile +1 | 1.0.9-3.el7 | RHSA-2017:1865 |
| RHEL 7 | mesa +16 | 17.0.1-6.20170307.el7 | RHSA-2017:1865 |
| RHEL 7 | mesa-private-llvm +1 | 3.9.1-3.el7 | RHSA-2017:1865 |
| RHEL 7 | vulkan +2 | 1.0.39.1-2.el7 | RHSA-2017:1865 |
| RHEL 7 | xcb-proto | 1.12-2.el7 | RHSA-2017:1865 |
| RHEL 7 | xkeyboard-config +1 | 2.20-1.el7 | RHSA-2017:1865 |
| RHEL 7 | xorg-x11-proto-devel | 7.7-20.el7 | RHSA-2017:1865 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | libXdmcp | 1.1.1-12.1 | SUSE-SU-2018:0338-1 |
| SLES 12 SP2 | libXdmcp | 1.1.1-10.1 | SUSE-SU-2017:1862-1 |
| SLES 11 SP4 | xorg-x11-libXdmcp | 7.4-3.1 | SUSE-SU-2017:1868-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP3 | libXdmcp | 1.1.1-12.1 | SUSE-SU-2018:0338-1 |
| SLES for SAP 12 SP2 | libXdmcp | 1.1.1-10.1 | SUSE-SU-2017:1862-1 |
| SLES for SAP 11 SP4 | xorg-x11-libXdmcp | 7.4-3.1 | SUSE-SU-2017:1868-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | libXdmcp | 1.1.3-1.11 | openSUSE-SU-2024:10920-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.23 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.22 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.21 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.20 | libxdmcp | 1.1.2-r3 | — |
Show 14 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.18 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.17 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.16 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.15 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.14 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.13 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.12 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.11 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.10 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.9 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.8 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.7 | libxdmcp | 1.1.2-r3 | — |
| Alpine v3.6 | libxdmcp | 1.1.2-r3 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | libICE +1 | 1.0.9-9.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libX11 +2 | 1.6.5-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXaw +1 | 1.0.13-4.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXcursor +1 | 1.1.14-8.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXdmcp +1 | 1.1.2-6.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXfixes +1 | 5.0.3-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXfont +1 | 1.5.2-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXfont2 +1 | 2.0.1-2.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXi +1 | 1.7.9-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXpm +1 | 3.5.12-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXrandr +1 | 1.5.1-2.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXrender +1 | 0.9.10-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXt +1 | 1.1.5-3.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXtst +1 | 1.2.3-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXv +1 | 1.0.11-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXvMC +1 | 1.0.10-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libXxf86vm +1 | 1.1.4-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libdrm +2 | 2.4.74-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libepoxy +1 | 1.3.1-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libevdev +2 | 1.5.6-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libfontenc +1 | 1.1.3-3.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libinput +1 | 1.6.3-2.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libvdpau +2 | 1.1.1-3.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libwacom +2 | 0.24-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libxcb +2 | 1.12-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libxkbcommon +3 | 0.7.1-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | libxkbfile +1 | 1.0.9-3.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | mesa-libGL +15 | 17.0.1-6.20170307.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | mesa-private-llvm +1 | 3.9.1-3.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | vulkan +2 | 1.0.39.1-2.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | xcb-proto | 1.12-2.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | xkeyboard-config +1 | 2.20-1.el7 | ELSA-2017-1865 |
| Oracle Linux 7 | xorg-x11-proto-devel | 7.7-20.el7 | ELSA-2017-1865 |
Advisories 7
- RHSA-2017:1865 Red Hat Security Advisory: X.org X11 libraries security, bug fix and enhancement update Red Hat Security Advisories (RHSA) · Jul 1, 2026
- USN-5690-1 libxdmcp vulnerability Ubuntu Security Notices (USN) · Jun 29, 2026
- SUSE-SU-2017:1868-1 Security update for xorg-x11-libXdmcp SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2018:0338-1 Security update for libXdmcp SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10920-1 libXdmcp-devel-1.1.3-1.11 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:1862-1 Security update for libXdmcp SUSE / openSUSE Security Updates · Feb 4, 2026
- ELSA-2017-1865 Moderate: X.org X11 libraries security, bug fix and enhancement update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Aug 7, 2017
References
- GLSA-201704-03 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-2625
- RHSA-2017:1865 vendor-advisory
- 1037919 vdb-entry
- https://cgit.freedesktop.org/xorg/lib/libXdmcp/commit/?id=0554324ec6bbc2071f5d1f8ad211a1643e29eb1f
- 96480 vdb-entry
- https://www.x41-dsec.de/lab/advisories/x41-2017-001-xorg/
- [debian-lts-announce] 20191125 [SECURITY] [DLA 2006-1] libxdmcp security update mailing-list