CVE-2026-55999

EUVD-2026-42188
Local attackers with a X connection able to provide PCX fonts to the X 
server xorg-server before 21.2.24 and xwayland before 24.1.13 could 
cause a heap buffer overflow via SetFont due to missing glyph boundary checks.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
8.5 HIGH
NETWORK
HIGH
LOW
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 19.24%
Affected Products (NVD)
VendorProductVersion
x.orgx_server
𝑥
< 21.2.24
x.orgxwayland
𝑥
< 24.1.13
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
xorg-server
bookworm
vulnerable
bookworm (security)
vulnerable
bullseye
vulnerable
bullseye (security)
vulnerable
forky
2:21.1.24-1
fixed
sid
2:21.1.24-1
fixed
trixie
vulnerable
trixie (security)
vulnerable
xwayland
bookworm
ignored
forky
2:24.1.13-1
fixed
sid
2:24.1.13-1
fixed
trixie
ignored
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
xorg
bionic
not-affected
focal
not-affected
jammy
not-affected
noble
not-affected
questing
not-affected
resolute
not-affected
xenial
not-affected
xorg-server
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
questing
ignored
resolute
needs-triage
trusty
needs-triage
xenial
needs-triage
xwayland
jammy
needs-triage
noble
needs-triage
questing
ignored
resolute
needs-triage
xorg-server-hwe-16.04
jammy
dne
noble
dne
questing
dne
resolute
dne
xenial
needs-triage
xorg-server-hwe-18.04
bionic
needs-triage
jammy
dne
noble
dne
questing
dne
resolute
dne
xorg-hwe-16.04
jammy
dne
noble
dne
questing
dne
resolute
dne
xenial
not-affected
xorg-hwe-18.04
bionic
not-affected
jammy
dne
noble
dne
questing
dne
resolute
dne
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
xorg-x11-server
suse enterprise desktop 15 SP7
21.1.15-150700.5.22.1
fixed
suse enterprise sap 15 SP7
21.1.15-150700.5.22.1
fixed
suse enterprise server 12 SP5
1.19.6-10.105.1
fixed
suse enterprise server 15 SP4
1.20.3-150400.38.74.1
fixed
suse enterprise server 15 SP5
21.1.4-150500.7.52.1
fixed
suse enterprise server 15 SP6
21.1.11-150600.5.31.1
fixed
suse enterprise server 15 SP7
21.1.15-150700.5.22.1
fixed
xorg-x11-server-Xvfb
suse enterprise desktop 15 SP7
21.1.15-150700.5.22.1
fixed
suse enterprise sap 15 SP7
21.1.15-150700.5.22.1
fixed
suse enterprise server 15 SP5
21.1.4-150500.7.52.1
fixed
suse enterprise server 15 SP6
21.1.11-150600.5.31.1
fixed
suse enterprise server 15 SP7
21.1.15-150700.5.22.1
fixed
xorg-x11-server-extra
suse enterprise desktop 15 SP7
21.1.15-150700.5.22.1
fixed
suse enterprise sap 15 SP7
21.1.15-150700.5.22.1
fixed
suse enterprise server 12 SP5
1.19.6-10.105.1
fixed
suse enterprise server 15 SP4
1.20.3-150400.38.74.1
fixed
suse enterprise server 15 SP5
21.1.4-150500.7.52.1
fixed
suse enterprise server 15 SP6
21.1.11-150600.5.31.1
fixed
suse enterprise server 15 SP7
21.1.15-150700.5.22.1
fixed
xorg-x11-server-sdk
suse enterprise server 15 SP4
1.20.3-150400.38.74.1
fixed
suse enterprise server 15 SP5
21.1.4-150500.7.52.1
fixed
suse enterprise server 15 SP6
21.1.11-150600.5.31.1
fixed
Red Hat logo
Red Hat Enterprise Linux Releases
Red Hat Product
Release
xorg-x11-server-Xdmx
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 8.4 AUS
0:1.20.10-5.el8_4.1
fixed
RHEL 8.6 AUS
0:1.20.11-8.el8_6.1
fixed
RHEL 8.8 E4S
0:1.20.11-19.el8_8.1
fixed
RHEL 8.8 TUS
0:1.20.11-19.el8_8.1
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
xorg-x11-server-Xephyr
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 8.4 AUS
0:1.20.10-5.el8_4.1
fixed
RHEL 8.6 AUS
0:1.20.11-8.el8_6.1
fixed
RHEL 8.8 E4S
0:1.20.11-19.el8_8.1
fixed
RHEL 8.8 TUS
0:1.20.11-19.el8_8.1
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
xorg-x11-server-Xnest
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 8.4 AUS
0:1.20.10-5.el8_4.1
fixed
RHEL 8.6 AUS
0:1.20.11-8.el8_6.1
fixed
RHEL 8.8 E4S
0:1.20.11-19.el8_8.1
fixed
RHEL 8.8 TUS
0:1.20.11-19.el8_8.1
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
xorg-x11-server-Xorg
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 8.4 AUS
0:1.20.10-5.el8_4.1
fixed
RHEL 8.6 AUS
0:1.20.11-8.el8_6.1
fixed
RHEL 8.8 E4S
0:1.20.11-19.el8_8.1
fixed
RHEL 8.8 TUS
0:1.20.11-19.el8_8.1
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
xorg-x11-server-Xvfb
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 8.4 AUS
0:1.20.10-5.el8_4.1
fixed
RHEL 8.6 AUS
0:1.20.11-8.el8_6.1
fixed
RHEL 8.8 E4S
0:1.20.11-19.el8_8.1
fixed
RHEL 8.8 TUS
0:1.20.11-19.el8_8.1
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
xorg-x11-server-Xwayland
RHEL 8.4 AUS
0:1.20.10-5.el8_4.1
fixed
RHEL 9
0:24.1.9-4.el9_8.3
fixed
xorg-x11-server-Xwayland-devel
RHEL 9
0:24.1.9-4.el9_8.3
fixed
xorg-x11-server-common
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 8.4 AUS
0:1.20.10-5.el8_4.1
fixed
RHEL 8.6 AUS
0:1.20.11-8.el8_6.1
fixed
RHEL 8.8 E4S
0:1.20.11-19.el8_8.1
fixed
RHEL 8.8 TUS
0:1.20.11-19.el8_8.1
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
xorg-x11-server-devel
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
xorg-x11-server-source
RHEL 8
0:1.20.11-28.el8_10.3
fixed
RHEL 9
0:1.20.11-34.el9_8.3
fixed
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
xorg-x11-server-Xdmx
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
xorg-x11-server-Xephyr
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xephyr-debuginfo
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xnest
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xnest-debuginfo
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xorg
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xorg-debuginfo
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xvfb
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xvfb-debuginfo
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-Xwayland
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:24.1.3-1.amzn2023.0.6
fixed
xorg-x11-server-Xwayland-debuginfo
Amazon Linux 2023
0:24.1.3-1.amzn2023.0.6
fixed
xorg-x11-server-Xwayland-debugsource
Amazon Linux 2023
0:24.1.3-1.amzn2023.0.6
fixed
xorg-x11-server-Xwayland-devel
Amazon Linux 2023
0:24.1.3-1.amzn2023.0.6
fixed
xorg-x11-server-common
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-debuginfo
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-debugsource
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-devel
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
xorg-x11-server-source
Amazon Linux 2
0:1.20.4-22.amzn2.0.13
fixed
Amazon Linux 2023
0:21.1.13-5.amzn2023.0.11
fixed
Common Weakness Enumeration
References
https://gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1
https://www.openwall.com/lists/oss-security/2026/07/08/2