CVE-2026-31624 HID: core: clamp report_size in s32ton() to avoid undefined shift
A malicious HID device can trigger an undefined shift in the Linux kernel, potentially causing a 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-2026-31624?
CVE-2026-31624 is a medium-severity vulnerability in Linux kernel, published on 24 Apr 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:
HID: core: clamp report_size in s32ton() to avoid undefined shift
s32ton() shifts by n-1 where n is the field's report_size, a value that comes directly from a HID device. The HID parser bounds report_size only to <= 256, so a broken HID device can supply a report descriptor with a wide field that triggers shift exponents up to 256 on a 32-bit type when an output report is built via hid_output_field() or hid_set_field().
Commit ec61b41918587 ("HID: core: fix shift-out-of-bounds in hid_report_raw_event") added the same n > 32 clamp to the function snto32(), but s32ton() was never given the same fix as I guess syzbot hadn't figured out how to fuzz a device the same way.
Fix this up by just clamping the max value of n, just like snto32() does.
Which versions are affected by CVE-2026-31624?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31624?
Apply the vendor's patch.
Is CVE-2026-31624 being exploited?
There is no known exploitation of CVE-2026-31624 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-83702, BELL-CVE-2026-31624, DEBIAN-CVE-2026-31624, GHSA-7r46-pv4v-9gxj, ROOT-OS-DEBIAN-11-CVE-2026-31624, ROOT-OS-DEBIAN-12-CVE-2026-31624 and 4 more.