CVE-2025-39727 mm: swap: fix potential buffer overflow in setup_clusters()

What is CVE-2025-39727?

CVE-2025-39727 is a high-severity memory corruption vulnerability in Linux kernel, published on 7 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

mm: swap: fix potential buffer overflow in setup_clusters()

In setup_swap_map(), we only ensure badpages are in range (0, last_page]. As maxpages might be < last_page, setup_clusters() will encounter a buffer overflow when a badpage is >= maxpages.

Only call inc_cluster_info_page() for badpage which is < maxpages to fix the issue.

Weakness: CWE-120

Which versions are affected by CVE-2025-39727?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-39727?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2025-39727 being exploited?

There is no known exploitation of CVE-2025-39727 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-39727, DEBIAN-CVE-2025-39727, GHSA-x952-wmpf-82wc, UBUNTU-CVE-2025-39727.