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CVE-2026-50257

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

Description (CNA)

A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Affected (CNA)

Vendor / productVersions
Red Hat / Red Hat Enterprise Linux 10unaffected 0:24.1.9-4.el10_2.2 before *
Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Supportunaffected 0:24.1.5-6.el10_0.1 before *
Red Hat / Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSIONunaffected 0:1.1.0-25.el6_10.18 before *
Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Supportunaffected 0:1.20.4-35.el7_9 before *
Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Supportunaffected 0:1.8.0-36.el7_9.5 before *
Red Hat / Red Hat Enterprise Linux 8unaffected 0:21.1.3-20.el8_10.2 before *
Red Hat / Red Hat Enterprise Linux 8unaffected 0:1.20.11-28.el8_10.2 before *
Red Hat / Red Hat Enterprise Linux 8unaffected 0:1.15.0-10.el8_10 before *
Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportunaffected 0:1.20.10-5.el8_4 before *
Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportunaffected 0:1.11.0-8.el8_4.16 before *
Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onunaffected 0:1.20.10-5.el8_4 before *
Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onunaffected 0:1.11.0-8.el8_4.16 before *
Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportunaffected 0:1.20.11-8.el8_6 before *
Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportunaffected 0:21.1.3-2.el8_6.7 before *
Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportunaffected 0:1.12.0-6.el8_6.18 before *
Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Onunaffected 0:1.20.11-8.el8_6 before *
Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Onunaffected 0:21.1.3-2.el8_6.7 before *
Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Onunaffected 0:1.12.0-6.el8_6.18 before *
Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Serviceunaffected 0:1.20.11-19.el8_8 before *
Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Serviceunaffected 0:21.1.3-13.el8_8.1 before *
Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Serviceunaffected 0:1.12.0-15.el8_8.18 before *
Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutionsunaffected 0:1.20.11-19.el8_8 before *
Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutionsunaffected 0:21.1.3-13.el8_8.1 before *
Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutionsunaffected 0:1.12.0-15.el8_8.18 before *
Red Hat / Red Hat Enterprise Linux 9unaffected 0:24.1.9-4.el9_8.2 before *
Red Hat / Red Hat Enterprise Linux 9unaffected 0:1.20.11-34.el9_8.2 before *
Red Hat / Red Hat Enterprise Linux 9unaffected 0:1.15.0-7.el9_8.2 before *
Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutionsunaffected 0:1.20.11-21.el9_2 before *
Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutionsunaffected 0:21.1.3-10.el9_2.1 before *
Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutionsunaffected 0:1.12.0-14.el9_2.15 before *
Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutionsunaffected 0:1.20.11-29.el9_4 before *
Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutionsunaffected 0:22.1.9-8.el9_4.1 before *
Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutionsunaffected 0:1.13.1-8.el9_4.10 before *
Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Supportunaffected 0:1.20.11-34.el9_6 before *
Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Supportunaffected 0:23.2.7-6.el9_6.1 before *
Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Supportunaffected 0:1.14.1-11.el9_6 before *
Red Hat / Red Hat Enterprise Linux 6unknown

CWE

CWE-416

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.