CVE-2026-55999

High

Description

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.

SeverityHigh

CVSS8.5

Exploit probability—

ProductX.org Xwayland

PublishedJul 8, 2026

First seenJul 8, 2026

Weakness typeCWE-122CWE-122

How to fix

Update

x.org xwayland24.1.13 or later
x.org x_server21.2.24 or later

Patches

gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1

Vendor advisories

openwall.com/lists/oss-security/2026/07/08/2

Affected products

Product	Affected versions	Fixed in
x.org xwayland	v < 24.1.13	24.1.13
x.org x_server	v < 21.2.24	21.2.24

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