CVE-2025-38257: Debian Linux

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: s390/pkey: Prevent overflow in size calculation for memdup_user() Number of apqn target list entries contained in 'nr_apqns' variable is determined by userspace via an ioctl call so the result of the product in calculation of size passed to memdup_user() may overflow. In this case the actual size of the allocated area and the value describing it won't be in sync leading to various types of unpredictable behaviour later. Use a proper memdup_array_user() helper which returns an error if an overflow is detected. Note that it is different from when nr_apqns is initially zero - that case is considered valid and should be handled in subsequent pkey_handler implementations. Found by Linux Verification Center (linuxtesting.org).

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: from 5.4, before 5.15.187 (fixed in 5.15.187); from 5.16, before 6.1.143 (fixed in 6.1.143); from 6.2, before 6.6.96 (fixed in 6.6.96); from 6.7, before 6.12.36 (fixed in 6.12.36); from 6.13, before 6.15.5 (fixed in 6.15.5); version 6.16 only

Published 2025-07-09. Last modified 2026-07-30.