CVE-2026-93078 cxl/features: Reject Set Features output buffer smaller than the header
A local attacker can trigger a kernel crash by providing a zero-length output buffer to the CXL Set Features command, causing a null pointer dereference.
- 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-2026-93078?
CVE-2026-93078 is a vulnerability in Linux, published on 17 Sep 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:
cxl/features: Reject Set Features output buffer smaller than the header
cxlctl_set_feature() sizes its output buffer from the user's fwctl_rpc.out_len but never checks it is large enough to hold even the fwctl_rpc_cxl_out header. With out_len == 0 , kvzalloc() returns ZERO_SIZE_PTR, which passes the !rpc_out check, the subsequent rpc_out->size = 0 then writes through the poison pointer.
Reject requests whose output buffer can't hold the response header, before allocating. The Set Feature reply carries no payload, so the header is all that is required.
Which versions are affected by CVE-2026-93078?
How do I fix CVE-2026-93078?
Apply the vendor's patch.
Is CVE-2026-93078 being exploited?
There is no known exploitation of CVE-2026-93078 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-93078, DEBIAN-CVE-2026-93078, GHSA-ww8v-32xc-j2p4, UBUNTU-CVE-2026-93078.