# CVE-2026-31624

> Vulnerability · severity: **MEDIUM** (CVSS 5.5).

## 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.

## Key facts

- **CVE ID:** CVE-2026-31624
- **Published:** 2026-04-24
- **CVSS severity:** MEDIUM
- **CVSS base score:** 5.5
- **CWE codes:** NVD-CWE-noinfo

## Affected products

- `linux:linux_kernel`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31624

## Citation

> AI Analytics. CVE-2026-31624. Retrieved 2026-08-08 from https://api.ai-analytics.org/cve/CVE-2026-31624. Derived from NIST NVD. Licensed CC0.

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