Detections
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RHEL 8 : xorg-x11-server-Xwayland (RHSA-2026:26562)
medium Nessus Plugin ID 321512
Synopsis
The remote Red Hat host is missing one or more security updates.Description
The remote Redhat Enterprise Linux 8 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2026:26562 advisory.Xwayland is an X server for running X clients under Wayland.
Security Fix(es):
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libXfont2 name length mismatch (CVE-2026-50256)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in miSyncDestroyFence() (CVE-2026-50257)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB key types due to unchecked shift levels (CVE-2026-50258)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB SetMap request via mapWidths indexing (CVE-2026-50259)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in FreeCounter() (CVE-2026-50260)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in SyncChangeCounter() (CVE-2026-50261)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: out-of-bounds read/write in GLX ChangeDrawableAttributes (CVE-2026-50262)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free information disclosure in CreateSaverWindow() (CVE-2026-50263)
* xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: out-of-bounds heap write in DRI2 DRIGetBuffers/DRIGetBuffersWithFormat (CVE-2026-50264)
Bug Fix(es) and Enhancement(s):
* [xwayland] Backport other security fixes without a CVE assigned [rhel-8.10.z] (JIRA:RHEL-184293)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
Solution
Update the affected xorg-x11-server-Xwayland package.See Also
https://access.redhat.com/security/updates/classification/#important
https://bugzilla.redhat.com/show_bug.cgi?id=2485385
https://bugzilla.redhat.com/show_bug.cgi?id=2485386
https://bugzilla.redhat.com/show_bug.cgi?id=2485380
https://bugzilla.redhat.com/show_bug.cgi?id=2485384
https://bugzilla.redhat.com/show_bug.cgi?id=2485389
https://bugzilla.redhat.com/show_bug.cgi?id=2485382
https://bugzilla.redhat.com/show_bug.cgi?id=2485383
https://bugzilla.redhat.com/show_bug.cgi?id=2485387
https://bugzilla.redhat.com/show_bug.cgi?id=2485388
Plugin Details
Severity: Medium
ID: 321512
File Name: redhat-RHSA-2026-26562.nasl
Version: 1.1
Type: Local
Agent: unix
Family: Red Hat Local Security Checks
Published: 6/18/2026
Updated: 6/18/2026
Supported Sensors: Nessus Agent, Continuous Assessment, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 6.7
Vendor
Vendor Severity: Important
CVSS v2
Risk Factor: Medium
Base Score: 6.8
Temporal Score: 5
Vector: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C
CVSS Score Source: CVE-2026-50264
CVSS v3
Risk Factor: Medium
Base Score: 5.5
Temporal Score: 4.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
CVSS Score Source: CVE-2026-50263
Vulnerability Information
CPE: cpe:/o:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xwayland, cpe:/o:redhat:rhel_eus:8.10
Required KB Items: Host/local_checks_enabled, Host/RedHat/release, Host/RedHat/rpm-list, Host/cpu
Exploit Ease: No known exploits are available
Patch Publication Date: 6/17/2026
Vulnerability Publication Date: 6/1/2026
Reference Information
CVE: CVE-2026-50256, CVE-2026-50257, CVE-2026-50258, CVE-2026-50259, CVE-2026-50260, CVE-2026-50261, CVE-2026-50262, CVE-2026-50263, CVE-2026-50264
RHSA: 2026:26562