CVE-2026-98201 Input: zero ff_effect before compat copy in input_ff_effect_from_user
A local attacker can read uninitialized kernel stack memory via the input subsystem's force feedback compatibility path, potentially leaking sensitive data.
- 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-2026-98201?
CVE-2026-98201 is a vulnerability in Linux, published on 6 Oct 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:
Input: zero ff_effect before compat copy in input_ff_effect_from_user
In the compat path input_ff_effect_from_user() aliases the caller's native struct ff_effect with the smaller struct ff_effect_compat and copies only the compat sized prefix:
compat_effect = (struct ff_effect_compat *)effect;
if (copy_from_user(compat_effect, buffer, sizeof(struct ff_effect_compat)))
The tail of the native structure is never written. Callers pass an uninitialized on-stack object, for example evdev_do_ioctl() for EVIOCSFF, so those bytes keep their previous stack contents. input_ff_upload() then stores the full native structure in ff->effects[id], from where a uinput based force feedback daemon can read it back via UI_BEGIN_FF_UPLOAD, disclosing kernel stack memory to userspace.
Zero the effect before the compat copy.
Which versions are affected by CVE-2026-98201?
How do I fix CVE-2026-98201?
Apply the vendor's patch.
Is CVE-2026-98201 being exploited?
There is no known exploitation of CVE-2026-98201 in the wild and no public exploit code.
Sources
Also known as AZL-106182, BELL-CVE-2026-98201, DEBIAN-CVE-2026-98201, GHSA-hc65-vq9g-6pfq, UBUNTU-CVE-2026-98201.