1. Home
  2. CVE Database
  3. CVE-2026-50256
HIGH · 7.8

CVE-2026-50256

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 ...

Vulnerability 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.

CVSS Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH

Affected Products

VendorProductVersions
X.OrgX Server< 21.1.23
X.OrgXwayland< 24.1.12
RedhatEnterprise Linux7.0

Related Weaknesses (CWE)

CWE-121

References

FAQ

What is CVE-2026-50256?

CVE-2026-50256 is a vulnerability with a CVSS score of 7.8 (HIGH). 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 ...

How severe is CVE-2026-50256?

CVE-2026-50256 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-50256?

Check the references section above for vendor advisories and patch information. Affected products include: X.Org X Server, X.Org Xwayland, Redhat Enterprise Linux.