CVE-2026-53154 mm/hugetlb: restore reservation on error in hugetlb folio copy paths
A resource leak in the Linux kernel hugetlb subsystem can cause SIGBUS errors and denial of service when copy operations fail.
- 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-2026-53154?
CVE-2026-53154 is a medium-severity denial of service vulnerability in Linux kernel, published on 25 Jun 2026. 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/hugetlb: restore reservation on error in hugetlb folio copy paths
Two sites in mm/hugetlb.c allocate a hugetlb folio via alloc_hugetlb_folio() (consuming a VMA reservation) and then call copy_user_large_folio(), which became int-returning in commit 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults") and can now fail (e.g. -EHWPOISON on a hwpoisoned source page). On the failure path, folio_put() restores the global hugetlb pool count through free_huge_folio(), but the per-VMA reservation map entry is left marked consumed:
- hugetlb_mfill_atomic_pte() resubmission path (UFFDIO_COPY) - copy_hugetlb_page_range() fork-time CoW path when hugetlb_try_dup_anon_rmap() fails (rare: pinned hugetlb anon folio under fork)
User-visible effect: on UFFDIO_COPY into a private hugetlb VMA where the resubmission copy fails, the reservation for that address is leaked from the VMA's reserve map. A subsequent fault at the same address takes the no-reservation path, and under hugetlb pool pressure the task is SIGBUSed at an address it had previously reserved. The fork-time CoW path leaks the same way in the child VMA's reserve map, though it requires the much rarer combination of pinned hugetlb anon page + hwpoisoned source.
Add the missing restore_reserve_on_error() call before folio_put() on both error paths.
Weakness: CWE-772
Which versions are affected by CVE-2026-53154?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53154?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-53154 being exploited?
There is no known exploitation of CVE-2026-53154 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90489, BELL-CVE-2026-53154, DEBIAN-CVE-2026-53154, GHSA-6828-fj37-mvwr, ROOT-OS-UBUNTU-2404-CVE-2026-53154, UBUNTU-CVE-2026-53154.