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CVE-2026-55999

xorg-server / xwayland glamor font atlas Heap Buffer Overflow

Published: Jul 8, 2026Updated: Jul 9, 2026 Sources: CVE List NVDCWE-122
8.5HIGH
NVD MITRE
EPSS Score
0.3%
Top 81.2%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:HPR:LUI:NS:CC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-122

Affected Products

X.Org
oss-project·US
x serverOn-prem
Operating Systems / unix-bsd
xwaylandOn-prem
Operating Systems / linux-distro
xorg-serverOn-premOS
Operating Systems / unix-bsd
and 1 more affected products View all →

Exploitability

Official Patch Available
Is your org exposed to CVE-2026-55999?We can run the check for you — a free external exposure review, no install. Check my exposure

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique
Privilege Escalation
View detailed technique mapping

References

https://gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1
gitlab.freedesktop.org
https://www.openwall.com/lists/oss-security/2026/07/08/2
openwall.com

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