CVE-2017-2625 — libXdmcp: weak entropy usage for session keys

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MEDIUM

libXdmcp: weak entropy usage for session keys

Published Jul 27, 2018

6.5

MEDIUM

CVSS 3.0

EPSS 0.53%

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 Xorg Product libXdmcp Default
n/a
- Version
  1.1.2
  Status
  affected
  Constraints
  -

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Xorg

libXdmcp

n/a

Version	Status	Constraints
1.1.2	affected	-

Red Hat Enterprise Linux 7

libICE-0:1.0.9-9.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libX11-0:1.6.5-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXaw-0:1.0.13-4.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXcursor-0:1.1.14-8.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXdmcp-0:1.1.2-6.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXfixes-0:5.0.3-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXfont-0:1.5.2-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXfont2-0:2.0.1-2.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXi-0:1.7.9-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXpm-0:3.5.12-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXrandr-0:1.5.1-2.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXrender-0:0.9.10-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXt-0:1.1.5-3.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXtst-0:1.2.3-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXv-0:1.0.11-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXvMC-0:1.0.10-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libXxf86vm-0:1.1.4-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libdrm-0:2.4.74-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libepoxy-0:1.3.1-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libevdev-0:1.5.6-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libfontenc-0:1.1.3-3.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libinput-0:1.6.3-2.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libvdpau-0:1.1.1-3.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libwacom-0:0.24-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libxcb-0:1.12-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libxkbcommon-0:0.7.1-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

libxkbfile-0:1.0.9-3.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

mesa-0:17.0.1-6.20170307.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

mesa-private-llvm-0:3.9.1-3.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

vulkan-0:1.0.39.1-2.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

xcb-proto-0:1.12-2.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

xkeyboard-config-0:2.20-1.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 7

xorg-x11-proto-devel-0:7.7-20.el7

Fixed · RHSA-2017:1865
Red Hat Enterprise Linux 5

libXdmcp

Will not fix
Red Hat Enterprise Linux 6

libXdmcp

Will not fix

Product	Package	State	Advisory
Red Hat Enterprise Linux 7	libICE-0:1.0.9-9.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libX11-0:1.6.5-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXaw-0:1.0.13-4.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXcursor-0:1.1.14-8.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXdmcp-0:1.1.2-6.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXfixes-0:5.0.3-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXfont-0:1.5.2-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXfont2-0:2.0.1-2.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXi-0:1.7.9-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXpm-0:3.5.12-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXrandr-0:1.5.1-2.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXrender-0:0.9.10-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXt-0:1.1.5-3.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXtst-0:1.2.3-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXv-0:1.0.11-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXvMC-0:1.0.10-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libXxf86vm-0:1.1.4-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libdrm-0:2.4.74-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libepoxy-0:1.3.1-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libevdev-0:1.5.6-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libfontenc-0:1.1.3-3.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libinput-0:1.6.3-2.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libvdpau-0:1.1.1-3.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libwacom-0:0.24-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libxcb-0:1.12-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libxkbcommon-0:0.7.1-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	libxkbfile-0:1.0.9-3.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	mesa-0:17.0.1-6.20170307.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	mesa-private-llvm-0:3.9.1-3.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	vulkan-0:1.0.39.1-2.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	xcb-proto-0:1.12-2.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	xkeyboard-config-0:2.20-1.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 7	xorg-x11-proto-devel-0:7.7-20.el7	Fixed	RHSA-2017:1865
Red Hat Enterprise Linux 5	libXdmcp	Will not fix	n/a
Red Hat Enterprise Linux 6	libXdmcp	Will not fix	n/a

Remediation

Red Hat statement

Red Hat Product Security has rated this issue as having Moderate security impact. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.

Metrics

0.53% 0.00534

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.

EPSS probability 0.00534

Score over time

2021–2026

EPSS v1
EPSS v5
EPSS v2
EPSS v3

Percentile over time

EPSS v1
EPSS v5
EPSS v2
EPSS v3

Table of values (8 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 1, 2026	0.53% (0.00534)	42.96th	v5 (v2026.06.15)
Sep 20, 2026	0.53% (0.00534)	43.98th	v5 (v2026.06.15)
Jul 20, 2024	0.04% (0.00042)	5.06th	v3 (v2023.03.01)
Mar 7, 2023	0.04% (0.00042)	5.63th	v3 (v2023.03.01)
Mar 6, 2023	1.10% (0.01104)	54.09th	v2 (v2022.01.01)
Feb 4, 2022	1.10% (0.01104)	28.85th	v2 (v2022.01.01)
Feb 3, 2022	1.00% (0.00999)	27.22th	v5 (v2026.06.15)
Apr 14, 2021	1.00% (0.00999)	0.00th	v1

Weaknesses (2)

CWE-320

CWE-331

References (12)

http://www.securityfocus.com/bid/96480
vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1037919
vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry
https://access.redhat.com/errata/RHSA-2017:1865
vendor-advisoryx_refsource_REDHATThird Party Advisory
https://access.redhat.com/security/cve/CVE-2017-2625
Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1424987
Issue Tracking
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-2625
x_refsource_CONFIRMIssue TrackingThird Party Advisory
https://cgit.freedesktop.org/xorg/lib/libXdmcp/commit/?id=0554324ec6bbc2071f5d1f8ad211a1643e29eb1f
x_refsource_CONFIRMThird Party Advisory
https://lists.debian.org/debian-lts-announce/2019/11/msg00024.html
mailing-listx_refsource_MLIST
https://nvd.nist.gov/vuln/detail/CVE-2017-2625
https://security.gentoo.org/glsa/201704-03
vendor-advisoryx_refsource_GENTOOThird Party Advisory
https://www.cve.org/CVERecord?id=CVE-2017-2625
https://www.x41-dsec.de/lab/advisories/x41-2017-001-xorg/
x_refsource_MISCExploitThird Party Advisory

Link	Providers	Tags
http://www.securityfocus.com/bid/96480		vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1037919		vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry
https://access.redhat.com/errata/RHSA-2017:1865		vendor-advisoryx_refsource_REDHATThird Party Advisory
https://access.redhat.com/security/cve/CVE-2017-2625		Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1424987		Issue Tracking
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-2625		x_refsource_CONFIRMIssue TrackingThird Party Advisory
https://cgit.freedesktop.org/xorg/lib/libXdmcp/commit/?id=0554324ec6bbc2071f5d1f8ad211a1643e29eb1f		x_refsource_CONFIRMThird Party Advisory
https://lists.debian.org/debian-lts-announce/2019/11/msg00024.html		mailing-listx_refsource_MLIST
https://nvd.nist.gov/vuln/detail/CVE-2017-2625
https://security.gentoo.org/glsa/201704-03		vendor-advisoryx_refsource_GENTOOThird Party Advisory
https://www.cve.org/CVERecord?id=CVE-2017-2625
https://www.x41-dsec.de/lab/advisories/x41-2017-001-xorg/		x_refsource_MISCExploitThird Party Advisory