CVE-2026-31624
Published: April 25, 2026Last modified: May 1, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 5.5 |
| Attack Vector | LOCAL |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | NONE |
| Integrity impact | NONE |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | linux-lts | Vulnerable (6.1.168-r0) |
| 25 LTS | linux-lts | Fixed (6.12.85-r0) | |
| Stream | linux-lts | Fixed (6.12.85-r0) |
References
- https://git.kernel.org/stable/c/58386f00af710922cafb0fb69211497beddfaa95
- https://git.kernel.org/stable/c/69c02ffde6ed4d535fa4e693a9e572729cad3d0d
- https://git.kernel.org/stable/c/8a8333237f1f5caab8d4c3d2c2e7578c4263a97f
- https://git.kernel.org/stable/c/932ae5309e53561197aa7d1606c7cf63af10e24f
- https://git.kernel.org/stable/c/97014719bb8fccb1ffcbbc299e84b1f11b114195
- https://git.kernel.org/stable/c/ea363a34086ddb4231adc581a7f36c39ec154bfc