Out-of-bounds Read in Linux

CVE-2025-38556

In the Linux kernel, the following vulnerability has been resolved: HID: core: Harden s32ton() against conversion to 0 bits Testing by the syzbot fuzzer showed that the HID core gets a shift-out-of-bounds exception when it tries to convert a 32-bit quantity to a 0-bit quantity. Ideally this should never occur, but there are buggy devices and some might have a report field with size set to zero; we shouldn't reject the report or the device just because of that. Instead, harden the s32ton() routine so that it returns a reasonable result instead of crashing when it is called with the number of bits set to 0 -- the same as what snto32() does.

Vulnerability class: Buffer Overflow

EPSS: 0.002 (5.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-38556?
CVE-2025-38556 is a high-severity vulnerability in Linux, classified under Out-of-bounds Read. CVSS score: 7.1/10. Published 2025-08-19.
How severe is CVE-2025-38556?
High severity. CVSS v3 base score is 7.1 out of 10.
Is CVE-2025-38556 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.