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.

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the 36cb0ced-5e23-11f1-86a2-589cfc10a551 advisory.

    X.Org project reports:
    Multiple issues have been found in the X server and Xwayland                  implementations published by X.Org for which we are releasing                  security fixes for in xorg-server-21.1.23 and xwayland-24.1.12.

Tenable has extracted the preceding description block directly from the FreeBSD security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the 592ced15-5e20-11f1-86a2-589cfc10a551 advisory.

    X.Org project reports:
    Multiple issues have been found in the X server and Xwayland                  implementations published by X.Org for which we are releasing                  security fixes for in xorg-server-21.1.23 and xwayland-24.1.12.

Tenable has extracted the preceding description block directly from the FreeBSD security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-50261)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
319308	FreeBSD : xwayland -- Multiple vulnerabilities (36cb0ced-5e23-11f1-86a2-589cfc10a551)	Nessus	FreeBSD Local Security Checks	high
319307	FreeBSD : xorg-server -- Multiple vulnerabilities (592ced15-5e20-11f1-86a2-589cfc10a551)	Nessus	FreeBSD Local Security Checks	high
318744	Linux Distros Unpatched Vulnerability : CVE-2026-50261	Nessus	Misc.	high

Detections

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CVE-2026-50261

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Tenable Plugins

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