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CVE-2026-50258 Details

Description

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: redhat-SADPCVSS-B:7.8 HIGHVector:CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://access.redhat.com/errata/RHSA-2026:26562 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:26566 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:26590 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:26610 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:26709 redhat-SADP

see all 64 references

Weakness Enumeration

CWE-IDCWE NameSource
CWE-121Stack-based Buffer Overflowredhat-SADP
CWE-121Stack-based Buffer Overflow[email protected]

Affected Products

ProductVersions
x.org x server
< 21.1.23

CPE

  • cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.
x.org xwayland
< 24.1.12

CPE

  • cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.
redhat enterprise linux
7.0
8.0
9.0
10.0

CPE

  • 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:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.

Change History

31 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2026-50258
NVD Published Date:
Jun 5, 2026
NVD Last Modified:
Aug 5, 2026
Source:
[email protected]
CVE-2026-50258 Details - Not Deferred