Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libxfont2 name length mismatch

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2026-50256
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-05 12:16:38 UTC
Updated2026-06-05 13:27:38 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-121 | CWE-121 Stack-based Buffer Overflow

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 9 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 9 Not specified Not specified

References

ReferenceSourceLinkTags
lists.x.org/archives/xorg-announce/2026-June/003702.html [email protected] lists.x.org
gitlab.freedesktop.org/xorg/xserver/-/commit/bb5158f962dc935e58ef8b4b5fcb31be201a6e07 [email protected] gitlab.freedesktop.org
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
redhat.atlassian.net/browse/PSIRTSUPT-16950 [email protected] redhat.atlassian.net
access.redhat.com/security/cve/CVE-2026-50256 [email protected] access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Upstream acknowledges Anonymous (Trend Micro Zero Day Initiative) as the original reporter. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-05-15T03:14:46.000ZReported to Red Hat.
CNA2026-06-02T00:00:00.000ZMade public.
© CVE.report 2026 |

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report