CVE-2026-63852

A flaw was found in the Linux kernel's AMD GPU (Graphics Processing Unit) Video Core Next (VCN) component. This vulnerability arises because the VCN encoder and decoder rings do not properly handle 64-bit user fence writes, leading to the rejection of command submissions that utilize these fences. An attacker could potentially exploit this to cause a denial of service by preventing legitimate operations that rely on 64-bit user fence writes.

This vulnerability is rated Moderate because exploitation requires local access and is constrained to systems utilizing specific AMD GPU hardware containing the Video Core Next (VCN) v4.0.3 block. On standard Red Hat Enterprise Linux installations where unprivileged users lack direct rendering manager device permissions or where affected AMD GPUs are not deployed, exposure is minimal. An attacker with local access could trigger a denial of service by causing command submission failures on the encoder ring, but the issue does not allow privilege escalation or unauthorized data access.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.