Integer Underflow (Wrap or Wraparound) Affecting xorg-server package, versions [,21.1.22)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-XORGSERVER-16304806
- published27 Apr 2026
- disclosed23 Apr 2026
- creditJan-Niklas Sohn
Introduced: 23 Apr 2026
CVE-2026-33999 (opens in a new tab)How to fix?
Upgrade xorg-server to version 21.1.22 or higher.
Overview
Affected versions of this package are vulnerable to Integer Underflow (Wrap or Wraparound) via the XkbSetCompatMap() function in the XKB compatibility map handling process. An attacker can cause memory-safety violations and potentially disrupt system availability by triggering a buffer read overrun through local or remote access to the X11 server.
Workaround
This vulnerability can be mitigated by restricting access to the X11 server. For remote access, disable X11 forwarding in SSH configurations by editing /etc/ssh/sshd_config and setting X11Forwarding no, then restarting the sshd service using systemctl restart sshd.