CVE-2025-39828: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-39828 is a vulnerability discovered in the Linux kernel's ATM TCP implementation. The vulnerability was disclosed on September 16, 2025, and affects the atmtcp subsystem. The issue specifically involves an arbitrary write vulnerability in the atmtcprecvcontrol() function (NVD).

The vulnerability exists in the atmtcprecvcontrol() function of the Linux kernel's ATM TCP implementation. When atmtcpvopen() or atmtcpvclose() is called via connect() or close(), atmtcpsendcontrol() is called to send an in-kernel special message. The vulnerability stems from the fact that sendmsg() does not validate the message length, allowing userspace to abuse atmtcprecvcontrol() to perform arbitrary writes through atmtcpcontrol. The struct atmtcpcontrol, which is part of the user API, contains space for an in-kernel pointer, creating the potential security risk (NVD).

The vulnerability could allow an attacker to perform arbitrary writes in kernel memory, potentially leading to privilege escalation or system compromise. The issue affects the Linux kernel's ATM TCP implementation and has been included in security updates for various Linux distributions (Debian Security).

The vulnerability has been addressed in Linux kernel updates. Debian has released security updates fixing this issue in version 6.1.153-1 for the oldstable distribution (bookworm) and version 6.12.48-1 for the stable distribution (trixie). Users are recommended to upgrade their Linux kernel packages to the patched versions (Debian Security).