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
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: 20%
Debian logo
Debian Releases
Debian Product
Codename
xorg-server
bookworm
vulnerable
bookworm (security)
vulnerable
bullseye
vulnerable
bullseye (security)
vulnerable
forky
vulnerable
sid
vulnerable
trixie
vulnerable
trixie (security)
vulnerable
xwayland
bookworm
ignored
forky
vulnerable
sid
vulnerable
trixie
ignored
Common Weakness Enumeration
Vulnerability Media Exposure
References
https://gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1
https://www.openwall.com/lists/oss-security/2026/07/08/2