Description
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Published: 2026-06-05
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DSA Debian DSA DSA-6370-1 xorg-server security update
History

Thu, 25 Jun 2026 14:00:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:9
References

Wed, 24 Jun 2026 11:15:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:8
References

Mon, 22 Jun 2026 08:00:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:10.2
References

Thu, 18 Jun 2026 04:45:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:enterprise_linux:8::crb
cpe:/a:redhat:enterprise_linux:9::appstream
cpe:/a:redhat:enterprise_linux:9::crb
References

Wed, 17 Jun 2026 12:45:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:enterprise_linux:8::appstream
References

Wed, 10 Jun 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Mon, 08 Jun 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared X.org x Server
X.org xwayland
CPEs cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
Vendors & Products X.org x Server
X.org xwayland

Sun, 07 Jun 2026 11:30:00 +0000

Type Values Removed Values Added
First Time appeared X.org
X.org xorg-server
Vendors & Products X.org
X.org xorg-server

Fri, 05 Jun 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Fri, 05 Jun 2026 11:45:00 +0000

Type Values Removed Values Added
Description A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Title Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libxfont2 name length mismatch
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-121
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Subscriptions

Redhat Enterprise Linux
X.org X Server Xorg-server Xwayland
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-06-25T13:16:04.915Z

Reserved: 2026-06-04T14:55:24.011Z

Link: CVE-2026-50256

cve-icon Vulnrichment

Updated: 2026-06-09T18:46:36.224Z

cve-icon NVD

Status : Analyzed

Published: 2026-06-05T12:16:38.727

Modified: 2026-06-08T16:45:14.903

Link: CVE-2026-50256

cve-icon Redhat

Severity : Important

Publid Date: 2026-06-02T00:00:00Z

Links: CVE-2026-50256 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-06-07T11:17:13Z

Weaknesses