CVE-2026-34001High· 7.8▾ TwilightA flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this witho…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 42.9 · 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
0.3%
A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.
xorg-x11-server-Xwayland (all versions)xorg-x11-server-Xwayland (all versions)xorg-x11-server-Xwayland (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)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 (all versions)xorg-x11-server-Xwayland (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-serverRefer to the linked advisories for vendor-supplied fixes and affected version ranges.
To mitigate this issue, restrict access to the X11 server to trusted users and networks. If the X.Org X server is not required, consider disabling or uninstalling it. For environments where the X server is essential, running X applications within a sandboxed environment can help reduce the attack surface.
Connected by shared product, vendor, weakness, or advisory.
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