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CVE-2026-50260

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in freecounter()

HIGH
7.8
CVSS Score
Published: June 5, 2026 at 10:36 AM UTC
Updated: September 28, 2026 at 11:46 AM UTC
3 products affected across 2 vendorsEnterprise LinuxX serverXwayland

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Severity
HIGH7.8
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

A use-after-free flaw was found in the X.Org X server and Xwayland in FreeCounter(). A client that sets up multiple SyncCounters and awaits on those triggers can trigger a use-after-free when destroying those counters via a second client connection. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Enterprise Linux· Red Hatrpm
95%
10.07.08.09.0
Vendor states this is fixed in 0:1.1.0-25.el6_10.18 (unaffected)
Vendor states this is fixed in 0:1.11.0-8.el8_4.16 (unaffected)
Vendor states this is fixed in 0:1.12.0-14.el9_2.15 (unaffected)
Vendor states this is fixed in 0:1.12.0-15.el8_8.18 (unaffected)
Vendor states this is fixed in 0:1.12.0-6.el8_6.18 (unaffected)
Vendor states this is fixed in 0:1.13.1-8.el9_4.10 (unaffected)
Vendor states this is fixed in 0:1.14.1-11.el9_6 (unaffected)
Vendor states this is fixed in 0:1.15.0-10.el8_10 (unaffected)
Vendor states this is fixed in 0:1.15.0-7.el9_8.2 (unaffected)
Vendor states this is fixed in 0:1.20.10-5.el8_4 (unaffected)
Vendor states this is fixed in 0:1.20.11-19.el8_8 (unaffected)
Vendor states this is fixed in 0:1.20.11-21.el9_2 (unaffected)
Vendor states this is fixed in 0:1.20.11-28.el8_10.2 (unaffected)
Vendor states this is fixed in 0:1.20.11-29.el9_4 (unaffected)
Vendor states this is fixed in 0:1.20.11-34.el9_6 (unaffected)
Vendor states this is fixed in 0:1.20.11-34.el9_8.2 (unaffected)
Vendor states this is fixed in 0:1.20.11-8.el8_6 (unaffected)
Vendor states this is fixed in 0:1.20.4-35.el7_9 (unaffected)
Vendor states this is fixed in 0:1.8.0-36.el7_9.5 (unaffected)
Vendor states this is fixed in 0:21.1.3-10.el9_2.1 (unaffected)
Vendor states this is fixed in 0:21.1.3-13.el8_8.1 (unaffected)
Vendor states this is fixed in 0:21.1.3-2.el8_6.7 (unaffected)
Vendor states this is fixed in 0:21.1.3-20.el8_10.2 (unaffected)
Vendor states this is fixed in 0:22.1.9-8.el9_4.1 (unaffected)
Vendor states this is fixed in 0:23.2.7-6.el9_6.1 (unaffected)
Vendor states this is fixed in 0:24.1.5-6.el10_0.1 (unaffected)
Vendor states this is fixed in 0:24.1.9-4.el10_2.2 (unaffected)
Vendor states this is fixed in 0:24.1.9-4.el9_8.2 (unaffected)
Vendor states this is fixed in 6 (unknown)
X server· X Org
95%
v < 21.1.23
Affected range stops below 21.1.23, so it looks safe — our inference, not a vendor statement
Xwayland· X Org
95%
v < 24.1.12
Affected range stops below 24.1.12, so it looks safe — our inference, not a vendor statement

References (34)

VDB Entryx_refsource_REDHATThird Party Advisory
Source: cverecord
https://access.redhat.com/security/cve/CVE-2026-50260
Issue Trackingx_refsource_REDHATThird Party Advisory
Source: cverecord
https://bugzilla.redhat.com/show_bug.cgi?id=2485385
Patch
Source: cverecord
https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b
Mailing ListVendor Advisory
Source: cverecord
https://lists.x.org/archives/xorg-announce/2026-June/003702.html
Permissions Required
Source: cverecord
https://redhat.atlassian.net/browse/PSIRTSUPT-16950
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:26562
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:26590
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:26610

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHredhat
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-416

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