Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-08-15T00:00:00 kernel: s390/monwriter: Reject buffer reuse with different data length 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-787

In the Linux kernel, the following vulnerability has been resolved: s390/monwriter: Reject buffer reuse with different data length When data buffers are reused, e.g. for interval sample records, the first record determines the data length, and the size of the buffer for user copy. Current monwriter code does not check if the data length was changed for subsequent records, which also would never happen for valid user programs. However, a malicious user could change the data length, resulting in out of bounds user copy to the kernel buffer, and memory corruption. By default, the monwriter misc device is created with root-only permissions, so practical impact is typically low. Fix this by checking for changed data length and rejecting such records.

A flaw was found in the Linux kernel's s390/monwriter component. This vulnerability allows a malicious local user with elevated privileges to cause memory corruption. By changing the data length during buffer reuse, the `monwriter` code fails to validate the new length, leading to an out-of-bounds write to the kernel buffer. While the `monwriter` device typically requires root permissions, successful exploitation could lead to system instability or further compromise.

Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Fix deferred kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-72025 https://nvd.nist.gov/vuln/detail/CVE-2026-72025 https://lore.kernel.org/linux-cve-announce/2026081510-CVE-2026-72025-3a2a@gregkh/T