Key points
- X.Org Server has released an update to fix CVE-2026-93516.
- The flaw allows local attackers to disclose sensitive information.
- Zero Day Initiative rated the vulnerability at 5.5 on the CVSS scale.
X.Org Server administrators should apply the latest update immediately to address CVE-2026-93516. This patch resolves an information disclosure vulnerability within the XInput Passive Grab functionality. The flaw involves a use-after-free error when handling DeviceInt objects. Without proper validation, attackers can exploit this issue to access sensitive data on affected systems.
In plain English
The problem occurs because the software fails to check if an object still exists before trying to use it. This is known as a use-after-free error. In this case, it happens within the DeviceInt handling code. An attacker who has already gained low-privileged access to the system can trigger this flaw. This allows them to read memory they should not be able to see, potentially revealing sensitive system information.
The background
Zero Day Initiative reported this vulnerability to the vendor on August 25, 2026. The advisory was released publicly on October 15, 2026, in a coordinated disclosure. The ZDI assigned a CVSS score of 5.5 to the issue. While the base severity is moderate, the advisory notes that this flaw could be combined with other vulnerabilities to execute arbitrary code with root privileges.
What changes now
X.Org has issued a software update to correct the vulnerability. The fix is available in the X.Org Server repository. The specific commit addresses the lack of validation for object existence prior to operations. Users must install this update to protect their systems from local information disclosure attacks. The patch ensures that the software properly checks for valid objects before processing them.
Who needs to act first
Teams should prioritize updating systems that expose X.Org Server to untrusted local users. Check whether your environment allows multiple users or services to run with low privileges on the same machine. Roll out the fix to exposed systems first, then move to isolated internal servers. Test the update in a non-production environment to ensure compatibility with existing input devices and applications. Back up configuration files before applying changes to facilitate quick recovery if issues arise. Monitor system logs after deployment to verify that input handling remains stable and no unexpected errors occur during normal operations.
What to do and how to stay safe: X.Org Server
- Install the latest X.Org Server update to patch CVE-2026-93516.
- Audit local user permissions to limit access to systems running X.Org.
- Monitor system logs for unusual activity related to input device handling.
- Review other installed components for potential chained vulnerabilities.
Step-by-step guide: Emergency Patching: How to Fix Critical Flaws Without Breaking Systems
General security guidance from the Patch Review newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is the CVSS score for this vulnerability?
Zero Day Initiative assigned a CVSS rating of 5.5 to CVE-2026-93516.
Can this flaw lead to remote code execution?
No, the advisory states that an attacker must first obtain the ability to execute low-privileged code on the target system.
Is a fix available for this issue?
Yes, X.Org has issued an update to correct this vulnerability, available in their repository.
