Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb key types due to unchecked shift levels

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Summary

CVECVE-2026-50258
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-05 12:16:39 UTC
Updated2026-07-15 01:16:17 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from ADP

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

EPSS: 0.001610000 probability, percentile 0.056960000 (date 2026-07-16)

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

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1[email protected]Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.8HIGHCVSS: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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Redhat Enterprise Linux 10.0 All All All
Operating System Redhat Enterprise Linux 7.0 All All All
Operating System Redhat Enterprise Linux 8.0 All All All
Operating System Redhat Enterprise Linux 9.0 All All All
Application X.org Xwayland All All All All
Application X.org X Server All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Enterprise Linux 10 unaffected 0:24.1.9-4.el10_2.2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support unaffected 0:24.1.5-6.el10_0.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support unaffected 0:1.20.4-35.el7_9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 0:21.1.3-20.el8_10.2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 0:1.20.11-28.el8_10.2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 0:1.15.0-10.el8_10 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support unaffected 0:1.20.10-5.el8_4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On unaffected 0:1.20.10-5.el8_4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support unaffected 0:1.20.11-8.el8_6 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support unaffected 0:21.1.3-2.el8_6.7 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On unaffected 0:1.20.11-8.el8_6 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On unaffected 0:21.1.3-2.el8_6.7 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service unaffected 0:1.20.11-19.el8_8 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service unaffected 0:21.1.3-13.el8_8.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions unaffected 0:1.20.11-19.el8_8 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions unaffected 0:21.1.3-13.el8_8.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:24.1.9-4.el9_8.2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:1.20.11-34.el9_8.2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:1.15.0-7.el9_8.2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:1.20.11-21.el9_2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:21.1.3-10.el9_2.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.4 Update Services For SAP Solutions unaffected 0:1.20.11-29.el9_4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.4 Update Services For SAP Solutions unaffected 0:22.1.9-8.el9_4.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support unaffected 0:1.20.11-34.el9_6 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support unaffected 0:23.2.7-6.el9_6.1 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 6 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
ADP Red Hat Red Hat Enterprise Linux 10 unaffected 0:24.1.9-4.el10_2.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support unaffected 0:24.1.5-6.el10_0.1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support unaffected 0:1.20.4-35.el7_9 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 0:21.1.3-20.el8_10.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 0:1.20.11-28.el8_10.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 0:1.15.0-10.el8_10 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support unaffected 0:1.20.10-5.el8_4 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On unaffected 0:1.20.10-5.el8_4 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support unaffected 0:1.20.11-8.el8_6 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support unaffected 0:21.1.3-2.el8_6.7 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On unaffected 0:1.20.11-8.el8_6 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On unaffected 0:21.1.3-2.el8_6.7 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service unaffected 0:1.20.11-19.el8_8 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service unaffected 0:21.1.3-13.el8_8.1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions unaffected 0:1.20.11-19.el8_8 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions unaffected 0:21.1.3-13.el8_8.1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9 unaffected 0:24.1.9-4.el9_8.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9 unaffected 0:1.20.11-34.el9_8.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9 unaffected 0:1.15.0-7.el9_8.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:1.20.11-21.el9_2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:21.1.3-10.el9_2.1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.4 Update Services For SAP Solutions unaffected 0:1.20.11-29.el9_4 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.4 Update Services For SAP Solutions unaffected 0:22.1.9-8.el9_4.1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support unaffected 0:1.20.11-34.el9_6 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support unaffected 0:23.2.7-6.el9_6.1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/errata/RHSA-2026:36798 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com Issue Tracking, Third Party Advisory
access.redhat.com/errata/RHSA-2026:36792 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:26562 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:38502 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:36768 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/security/cve/CVE-2026-50258 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com Third Party Advisory
access.redhat.com/errata/RHSA-2026:36633 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
lists.x.org/archives/xorg-announce/2026-June/003702.html [email protected] lists.x.org Mailing List, Third Party Advisory
gitlab.freedesktop.org/xorg/xserver/-/commit/543e108516428fc8c3bea91d6563ad266f9a801e [email protected] gitlab.freedesktop.org Patch
access.redhat.com/errata/RHSA-2026:28923 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:26590 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:36634 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:29844 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-50258.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
access.redhat.com/errata/RHSA-2026:26709 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:36083 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:36086 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
redhat.atlassian.net/browse/PSIRTSUPT-16950 [email protected] redhat.atlassian.net Permissions Required
access.redhat.com/errata/RHSA-2026:36087 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:38810 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:36791 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:36085 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:26566 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:26610 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:36632 0b0ca135-0b70-47e7-9f44-1890c2a1c46c 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.
ADP2026-05-15T03:14:46.000ZReported to Red Hat.
ADP2026-06-02T00:00:00.000ZMade public.

Solutions

ADP: RHSA-2026:36083: Red Hat Enterprise Linux Server (v. 7 ELS), Red Hat Enterprise Linux Server Optional (v. 7 ELS)

ADP: RHSA-2026:36798: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)

ADP: RHSA-2026:26566: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)

ADP: RHSA-2026:28923: Red Hat Enterprise Linux AppStream (v. 8)

ADP: RHSA-2026:26709: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8)

ADP: RHSA-2026:26562: Red Hat Enterprise Linux AppStream (v. 8)

ADP: RHSA-2026:36792: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)

ADP: RHSA-2026:36791: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)

ADP: RHSA-2026:38810: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)

ADP: RHSA-2026:36768: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)

ADP: RHSA-2026:38502: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)

ADP: RHSA-2026:36086: Red Hat Enterprise Linux AppStream E4S (v.9.2)

ADP: RHSA-2026:36633: Red Hat Enterprise Linux AppStream E4S (v.9.2)

ADP: RHSA-2026:36087: Red Hat Enterprise Linux AppStream E4S (v.9.4)

ADP: RHSA-2026:36632: Red Hat Enterprise Linux AppStream E4S (v.9.4)

ADP: RHSA-2026:36085: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6)

ADP: RHSA-2026:36634: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6)

ADP: RHSA-2026:29844: Red Hat Enterprise Linux AppStream (v. 9)

ADP: RHSA-2026:26610: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)

ADP: RHSA-2026:26590: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)

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