CVE-2025-68292 mm/memfd: fix information leak in hugetlb folios
Local attackers can read uninitialized kernel memory via memfd hugetlb folios, potentially exposing sensitive data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-68292?
CVE-2025-68292 is a vulnerability in Linux, published on 16 Dec 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/memfd: fix information leak in hugetlb folios
When allocating hugetlb folios for memfd, three initialization steps are missing:
1. Folios are not zeroed, leading to kernel memory disclosure to userspace 2. Folios are not marked uptodate before adding to page cache 3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache()
The memfd allocation path bypasses the normal page fault handler (hugetlb_no_page) which would handle all of these initialization steps. This is problematic especially for udmabuf use cases where folios are pinned and directly accessed by userspace via DMA.
Fix by matching the initialization pattern used in hugetlb_no_page(): - Zero the folio using folio_zero_user() which is optimized for huge pages - Mark it uptodate with folio_mark_uptodate() - Take hugetlb_fault_mutex before adding to page cache to prevent races
The folio_zero_user() change also fixes a potential security issue where uninitialized kernel memory could be disclosed to userspace through read() or mmap() operations on the memfd.
Which versions are affected by CVE-2025-68292?
How do I fix CVE-2025-68292?
Apply the vendor's patch.
Is CVE-2025-68292 being exploited?
There is no known exploitation of CVE-2025-68292 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-68292, DEBIAN-CVE-2025-68292, GHSA-v2f5-67q3-rqpg, ROOT-OS-DEBIAN-13-CVE-2025-68292, UBUNTU-CVE-2025-68292.