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Advisory severityMedium6.5Vendor: HighRed Hat Linux

Medium [CVE-2026-56000] GLX contextTags Use-After-Free in CommonMakeCurrent

This medium-severity Red Hat Linux advisory covers CVE-2026-56000 affecting Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions, Red Hat Enterprise Linux 9.6 Extended Update Support.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-56000 Source published Source updated

VulniPulse record published Record updated

CVE-2026-56000
Affected products & platforms
Red Hat LinuxRed Hat Enterprise Linux
Open source advisory

Summary

Local attackers with a X connection able to provide GLX commit to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a Heap Use After Free, due to CommonMakeCurrent() pointing into potentially reallocated memory.

A flaw was found in the X.org X11 server, specifically within the GLX (OpenGL Extension to the X Window System) dispatch layer. A remote attacker can exploit this vulnerability by sending a series of crafted X11 requests.

This can lead to a use-after-free condition, where the server attempts to write data to memory that has already been released. The primary consequence of this memory corruption is a denial of service, potentially causing the X server to crash.

An Important use-after-free vulnerability in the X.org X11 server's GLX dispatch layer allows a remote, unauthenticated attacker to trigger a denial of service. This is considered Important due to the remote attack vector and the potential for unauthenticated denial of service.

Red Hat severity: Important — CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-825.

Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.6 Extended Update Support; Red Hat Enterprise Linux 8.

Is CVE-2026-56000 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-56000 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-56000?

Upgrade to a fixed release named by Red Hat:

  • xorg-x11-server-Xwayland-0:24.1.9-4.el10_2.3
  • xorg-x11-server-Xwayland-0:24.1.5-6.el10_0.2
  • xorg-x11-server-Xwayland-0:24.1.9-4.el9_8.3
  • xorg-x11-server-Xwayland-0:22.1.9-8.el9_4.3
  • xorg-x11-server-Xwayland-0:23.2.7-6.el9_6.3
  • RHSA-2026:38489
  • RHSA-2026:50100
  • RHSA-2026:38490
  • RHSA-2026:52398
  • RHSA-2026:50718

Confirm against the vendor advisory before you patch.

Affected versions
  • < 21.2.24
  • < 24.1.13

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Fixed versions
  • xorg-x11-server-Xwayland-0:24.1.9-4.el10_2.3
  • xorg-x11-server-Xwayland-0:24.1.5-6.el10_0.2
  • xorg-x11-server-Xwayland-0:24.1.9-4.el9_8.3
  • xorg-x11-server-Xwayland-0:22.1.9-8.el9_4.3
  • xorg-x11-server-Xwayland-0:23.2.7-6.el9_6.3
  • RHSA-2026:38489
  • RHSA-2026:50100
  • RHSA-2026:38490
  • RHSA-2026:52398
  • RHSA-2026:50718

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Mitigation

Upgrade to a fixed release: xorg-x11-server-Xwayland-0:24.1.9-4.el10_2.3, xorg-x11-server-Xwayland-0:24.1.5-6.el10_0.2, xorg-x11-server-Xwayland-0:24.1.9-4.el9_8.3, xorg-x11-server-Xwayland-0:22.1.9-8.el9_4.3, xorg-x11-server-Xwayland-0:23.2.7-6.el9_6.3, RHSA-2026:38489. That is the remediation for this advisory.

The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

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