Description
A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Red Hat Red Hat Enterprise Linux 10
Default version status: affected
0:24.1.9-4.el10_2.2 to < *unaffected
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
Default version status: affected
0:24.1.5-6.el10_0.1 to < *unaffected
Red Hat Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION
Default version status: affected
0:1.1.0-25.el6_10.18 to < *unaffected
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support
Default version status: affected
0:1.20.4-35.el7_9 to < *unaffected
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support
Default version status: affected
0:1.8.0-36.el7_9.5 to < *unaffected
Red Hat Red Hat Enterprise Linux 8
Default version status: affected
0:21.1.3-20.el8_10.2 to < *unaffected
Red Hat Red Hat Enterprise Linux 8
Default version status: affected
0:1.20.11-28.el8_10.2 to < *unaffected
Red Hat Red Hat Enterprise Linux 8
Default version status: affected
0:1.15.0-10.el8_10 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Default version status: affected
0:1.20.10-5.el8_4 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Default version status: affected
0:1.11.0-8.el8_4.16 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
Default version status: affected
0:1.20.10-5.el8_4 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
Default version status: affected
0:1.11.0-8.el8_4.16 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Default version status: affected
0:1.20.11-8.el8_6 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Default version status: affected
0:21.1.3-2.el8_6.7 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Default version status: affected
0:1.12.0-6.el8_6.18 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Default version status: affected
0:1.20.11-8.el8_6 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Default version status: affected
0:21.1.3-2.el8_6.7 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Default version status: affected
0:1.12.0-6.el8_6.18 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Default version status: affected
0:1.20.11-19.el8_8 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Default version status: affected
0:21.1.3-13.el8_8.1 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Default version status: affected
0:1.12.0-15.el8_8.18 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Default version status: affected
0:1.20.11-19.el8_8 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Default version status: affected
0:21.1.3-13.el8_8.1 to < *unaffected
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Default version status: affected
0:1.12.0-15.el8_8.18 to < *unaffected
Red Hat Red Hat Enterprise Linux 9
Default version status: affected
0:24.1.9-4.el9_8.2 to < *unaffected
Red Hat Red Hat Enterprise Linux 9
Default version status: affected
0:1.20.11-34.el9_8.2 to < *unaffected
Red Hat Red Hat Enterprise Linux 9
Default version status: affected
0:1.15.0-7.el9_8.2 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Default version status: affected
0:1.20.11-21.el9_2 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Default version status: affected
0:21.1.3-10.el9_2.1 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Default version status: affected
0:1.12.0-14.el9_2.15 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Default version status: affected
0:1.20.11-29.el9_4 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Default version status: affected
0:22.1.9-8.el9_4.1 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Default version status: affected
0:1.13.1-8.el9_4.10 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
Default version status: affected
0:1.20.11-34.el9_6 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
Default version status: affected
0:23.2.7-6.el9_6.1 to < *unaffected
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
Default version status: affected
0:1.14.1-11.el9_6 to < *unaffected
Red Hat Red Hat Enterprise Linux 6
Default version status: unknown
References
- https://access.redhat.com/errata/RHSA-2026:26562 ↗
- https://access.redhat.com/errata/RHSA-2026:26566 ↗
- https://access.redhat.com/errata/RHSA-2026:26590 ↗
- https://access.redhat.com/errata/RHSA-2026:26610 ↗
- https://access.redhat.com/errata/RHSA-2026:26709 ↗
- https://access.redhat.com/errata/RHSA-2026:28923 ↗
- https://access.redhat.com/errata/RHSA-2026:29844 ↗
- https://access.redhat.com/errata/RHSA-2026:36083 ↗
- https://access.redhat.com/errata/RHSA-2026:36085 ↗
- https://access.redhat.com/errata/RHSA-2026:36086 ↗
- https://access.redhat.com/errata/RHSA-2026:36087 ↗
- https://access.redhat.com/errata/RHSA-2026:36632 ↗
- https://access.redhat.com/errata/RHSA-2026:36633 ↗
- https://access.redhat.com/errata/RHSA-2026:36634 ↗
- https://access.redhat.com/errata/RHSA-2026:36768 ↗
- https://access.redhat.com/errata/RHSA-2026:36791 ↗
- https://access.redhat.com/errata/RHSA-2026:36792 ↗
- https://access.redhat.com/errata/RHSA-2026:36798 ↗
- https://access.redhat.com/errata/RHSA-2026:38502 ↗
- https://access.redhat.com/errata/RHSA-2026:38810 ↗
- https://access.redhat.com/errata/RHSA-2026:46377 ↗
- https://access.redhat.com/errata/RHSA-2026:46382 ↗
- https://access.redhat.com/errata/RHSA-2026:46385 ↗
- https://access.redhat.com/errata/RHSA-2026:46392 ↗
- https://access.redhat.com/errata/RHSA-2026:46456 ↗
- https://access.redhat.com/errata/RHSA-2026:46460 ↗
- https://access.redhat.com/errata/RHSA-2026:46473 ↗
- https://access.redhat.com/errata/RHSA-2026:49519 ↗
- https://access.redhat.com/security/cve/CVE-2026-50261 ↗
- https://bugzilla.redhat.com/show_bug.cgi?id=2485386 ↗
- https://gitlab.freedesktop.org/xorg/xserver/-/commit/bdd7bf57af208b1ddf57d4683d67104443b44812 ↗
- https://lists.x.org/archives/xorg-announce/2026-June/003702.html ↗
- https://redhat.atlassian.net/browse/PSIRTSUPT-16950 ↗
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-50261.json ↗