Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in syncchangecounter()
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.
Evidence and details
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-50261
Red Hat Enterprise Linux 10
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 10.0 Extended Update Support
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION
Source reference: /containers/cna/affected/2/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 7 Extended Lifecycle Support
Source reference: /containers/cna/affected/3/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 7 Extended Lifecycle Support
Source reference: /containers/cna/affected/4/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8
Source reference: /containers/cna/affected/5/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8
Source reference: /containers/cna/affected/6/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8
Source reference: /containers/cna/affected/7/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Source reference: /containers/cna/affected/8/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Source reference: /containers/cna/affected/9/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
Source reference: /containers/cna/affected/10/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
Source reference: /containers/cna/affected/11/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Source reference: /containers/cna/affected/12/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Source reference: /containers/cna/affected/13/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
Source reference: /containers/cna/affected/14/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Source reference: /containers/cna/affected/15/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Source reference: /containers/cna/affected/16/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
Source reference: /containers/cna/affected/17/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Source reference: /containers/cna/affected/18/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Source reference: /containers/cna/affected/19/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
Source reference: /containers/cna/affected/20/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Source reference: /containers/cna/affected/21/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Source reference: /containers/cna/affected/22/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Source reference: /containers/cna/affected/23/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9
Source reference: /containers/cna/affected/24/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9
Source reference: /containers/cna/affected/25/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9
Source reference: /containers/cna/affected/26/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Source reference: /containers/cna/affected/27/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Source reference: /containers/cna/affected/28/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
Source reference: /containers/cna/affected/29/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Source reference: /containers/cna/affected/30/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Source reference: /containers/cna/affected/31/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
Source reference: /containers/cna/affected/32/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.6 Extended Update Support
Source reference: /containers/cna/affected/33/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.6 Extended Update Support
Source reference: /containers/cna/affected/34/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 9.6 Extended Update Support
Source reference: /containers/cna/affected/35/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Red Hat Enterprise Linux 6
Source reference: /containers/cna/affected/36/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
- Related CVEs
- CVE-2026-50261
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics