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.

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00012.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Redhat Subscribe
Enterprise Linux Subscribe
X.org Subscribe
X Server Subscribe
Xorg-server Subscribe
Xwayland Subscribe

Configuration 1 [-]

OR cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

No data.

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Vendors Products
Redhat Subscribe
Enterprise Linux Subscribe
X.org Subscribe
Xorg-server Subscribe
Advisories
Source ID Title
Debian DLA Debian DLA DLA-4737-1 xorg-server security update
Debian DLA Debian DLA DLA-4738-1 xorg-server security update
Debian DSA Debian DSA DSA-6370-1 xorg-server security update
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://access.redhat.com/errata/RHSA-2026:26562 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:26566 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:26590 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:26610 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:26709 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:28923 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:29844 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36083 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36085 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36086 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36087 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36632 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36633 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36634 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36768 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36791 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36792 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:36798 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:38502 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:38810 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:46377 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:46382 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:46385 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:46392 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:46456 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:46460 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:46473 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:49519 cve-icon cve-icon
https://access.redhat.com/security/cve/CVE-2026-50256 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2485380 cve-icon cve-icon
https://gitlab.freedesktop.org/xorg/xserver/-/commit/bb5158f962dc935e58ef8b4b5fcb31be201a6e07 cve-icon cve-icon cve-icon
https://lists.x.org/archives/xorg-announce/2026-June/003702.html cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-50256 cve-icon
https://redhat.atlassian.net/browse/PSIRTSUPT-16950 cve-icon cve-icon cve-icon
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-50256.json cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-50256 cve-icon
History

Tue, 04 Aug 2026 23:45:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:rhel_els:6
References

Mon, 27 Jul 2026 10:15:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:7
References

Mon, 27 Jul 2026 07:45:00 +0000

Type Values Removed Values Added
References

Mon, 27 Jul 2026 06:30:00 +0000

Type Values Removed Values Added
References

Mon, 27 Jul 2026 04:00:00 +0000

Type Values Removed Values Added
References

Mon, 13 Jul 2026 12:00:00 +0000

Type Values Removed Values Added
References

Mon, 13 Jul 2026 05:30:00 +0000

Type Values Removed Values Added
References

Thu, 09 Jul 2026 04:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux Eus
Redhat rhel Tus
CPEs cpe:/a:redhat:rhel_e4s:8.8::appstream
cpe:/a:redhat:rhel_tus:8.8::appstream
cpe:/o:redhat:enterprise_linux_eus:10.0
Vendors & Products Redhat enterprise Linux Eus
Redhat rhel Tus
References

Wed, 08 Jul 2026 17:00:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:rhel_aus:8.4::appstream
cpe:/a:redhat:rhel_eus_long_life:8.4::appstream
References

Wed, 08 Jul 2026 16:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel Aus
Redhat rhel Eus Long Life
CPEs cpe:/a:redhat:rhel_aus:8.6::appstream
cpe:/a:redhat:rhel_eus_long_life:8.6::appstream
Vendors & Products Redhat rhel Aus
Redhat rhel Eus Long Life
References

Wed, 08 Jul 2026 10:00:00 +0000

Type Values Removed Values Added
References

Tue, 07 Jul 2026 12:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel Els
Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_e4s:9.4::appstream
cpe:/a:redhat:rhel_eus:9.6::appstream
cpe:/a:redhat:rhel_eus:9.6::crb
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Redhat rhel Eus
References

Tue, 07 Jul 2026 07:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel E4s
CPEs cpe:/a:redhat:rhel_e4s:9.2::appstream
Vendors & Products Redhat rhel E4s
References

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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-08-05T12:14:46.975Z

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

Link: CVE-2026-50256

cve-icon Vulnrichment

Updated: 2026-07-27T12:05:48.547Z

cve-icon NVD

Status : Modified

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

Modified: 2026-08-05T13:23:28.273

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