An integer underflow occurs in the XKB compatibility map processing of the X.Org X server, which can cause a memory‑safety violation through a buffer read overrun. This flaw can lead to a denial‑of‑service condition or other severe impacts. The vulnerability does not provide direct remote code execution but allows an attacker with access to the X11 server—either locally or over a remote connection—to trigger the failure.

Red Hat Enterprise Linux 9, 8, 7, 6, and 10 distributions are affected, specifically the Xorg/X11 server component that implements the XKB compatibility maps. No other vendors or products are listed as impacted in the CNA data.

The CVSS score of 7.8 classifies the issue as high severity. The EPSS indicator of less than 1% implies a very low likelihood of exploitation in the wild. The flaw is not catalogued in CISA KEV. Exploitation requires the attacker to gain access to the X11 server, which can be achieved locally or remotely via SSH X11 forwarding. Once an attacker can reach the XKB compatibility map handling code, they can trigger the integer underflow and consequent buffer read overrun to cause a service crash.