CVE-2026-74449 drm/amd/display: Fix divide-by-zero in calculate_mcache_setting on zero viewport
A divide-by-zero error in the AMD display driver causes a kernel panic when processing a zero-area viewport, leading to system denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74449?
CVE-2026-74449 is a high-severity denial of service vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Fix divide-by-zero in calculate_mcache_setting on zero viewport
If a plane reaches calculate_mcache_setting with a zero-area viewport, calculate_mcache_setting exits early with num_mcaches == 0 and mvmpg_width/height == 0. This will cause a divide-by-zero panic and can also cause an underflow on num_mcaches.
Fix this by changing calculate_mcache_setting to bool and adding guards after each calculate_mcache_row_bytes call. If num_mcaches or mvmpg_width/height is zero, return a false. Callers will propagate the failure as a rejected mode, which prevents the panic.
(cherry picked from commit 29c0f7c655f47bcbd575ff75e58480df6ec3c9da)
Which versions are affected by CVE-2026-74449?
How do I fix CVE-2026-74449?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-74449 being exploited?
There is no known exploitation of CVE-2026-74449 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74449, DEBIAN-CVE-2026-74449, GHSA-2qf4-qh24-m72c, UBUNTU-CVE-2026-74449.