CVE-2026-34000Medium· 6.1▾ SunlitA flaw was found in the X.Org X server. This out-of-bounds read vulnerability in the XKB geometry processing, specifically within the `CheckSetGeom()` and `XkbAddGeomKeyAlias` functions, allows an attacker to read uninitialized or out-of…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 33.6 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.5%
A flaw was found in the X.Org X server. This out-of-bounds read vulnerability in the XKB geometry processing, specifically within the CheckSetGeom() and XkbAddGeomKeyAlias functions, allows an attacker to read uninitialized or out-of-bounds memory. An attacker with a connection to the X11 server, either locally or remotely, can exploit this without user interaction. This could lead to the disclosure of memory contents or cause a denial of service by crashing the server.
xorg-x11-server-Xwayland (all versions)tigervnc (all versions)xorg-x11-server (all versions)tigervnc (all versions)xorg-x11-server (all versions)tigervnc (all versions)xorg-x11-server (all versions)tigervnc (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)tigervnc (all versions)tigervnc (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)tigervnc (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)tigervnc (all versions)tigervnc (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)tigervnc (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)tigervnc (all versions)xorg-x11-server (all versions)xorg-x11-server-Xwayland (all versions)tigervnc (all versions)xorg-x11-server (all versions)xorg-x11-server-Xwayland (all versions)tigervnc (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-servertigervnc (all versions)xorg-x11-server (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server (all versions)xorg-x11-server-Xwayland (all versions)Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
To mitigate this vulnerability, restrict access to the X11 server. On systems where a graphical environment is not required, consider disabling the X server entirely by setting the default system target to multi-user mode. For systems requiring the X server, ensure that X11 forwarding is disabled in SSH configurations if not explicitly needed, and restrict direct X11 connections to trusted users and networks through firewall rules. If changes are made to SSH configuration, the sshd service must be restarted. If the default system target is changed, a system reboot is required.
Connected by shared product, vendor, weakness, or advisory.
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