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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-50259

35
FAUCET Score

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.

First published: Jun 5, 2026Last modified: Jul 27, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 21.1.23CPE matchmatch criteria
cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
< 24.1.12CPE matchmatch criteria
cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

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 Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.17%
Probability of exploitation in next 30 days
EPSS Percentile
6.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0016 is in the 26th percentile among its peer group of 17,061 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

microsoftpatch availablevia msrc
Product: azl3 xorg-x11-server-Xwayland 24.1.6-4 on Azure Linux 3.0Fixed in: 24.1.12-1
microsoftpatch availablevia msrc
Product: 21316-17084Fixed in: 24.1.12-1

Vendor Advisories (1)

microsoft2026-Jun/CVE-2026-50259Important

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb setmap request via mapwidths indexing

Jun 9, 2026

References

security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-50259.json
access.redhat.com / errata/RHSA-2026:26562
access.redhat.com / errata/RHSA-2026:26566
access.redhat.com / errata/RHSA-2026:26590
access.redhat.com / errata/RHSA-2026:26610
access.redhat.com / errata/RHSA-2026:26709
access.redhat.com / errata/RHSA-2026:28923
access.redhat.com / errata/RHSA-2026:29844
access.redhat.com / errata/RHSA-2026:36083
access.redhat.com / errata/RHSA-2026:36085
access.redhat.com / errata/RHSA-2026:36086
access.redhat.com / errata/RHSA-2026:36087
access.redhat.com / errata/RHSA-2026:36632
access.redhat.com / errata/RHSA-2026:36633
access.redhat.com / errata/RHSA-2026:36634
access.redhat.com / errata/RHSA-2026:36768
access.redhat.com / errata/RHSA-2026:36791
access.redhat.com / errata/RHSA-2026:36792
access.redhat.com / errata/RHSA-2026:36798
access.redhat.com / errata/RHSA-2026:38502
access.redhat.com / errata/RHSA-2026:38810
access.redhat.com / errata/RHSA-2026:46377
access.redhat.com / errata/RHSA-2026:46382
access.redhat.com / errata/RHSA-2026:46385
access.redhat.com / errata/RHSA-2026:46392
access.redhat.com / errata/RHSA-2026:46456
access.redhat.com / errata/RHSA-2026:46460
access.redhat.com / errata/RHSA-2026:46473
access.redhat.com / security/cve/CVE-2026-50259
Third Party Advisory
bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory
gitlab.freedesktop.org / xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eacf6e00b
Patch
lists.x.org / archives/xorg-announce/2026-June/003702.html
Mailing ListThird Party Advisory
redhat.atlassian.net / browse/PSIRTSUPT-16950
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