CVE-2026-64416

CVE Details

Release Date:	2026-07-25
Impact:	Moderate	What is this?

Description

In the Linux kernel, the following vulnerability has been resolved: mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host lookup_swap_cgroup_id() passes swap_cgroup_ctrl[type].map to __swap_cgroup_id_lookup() without checking that the type was ever registered via swap_cgroup_swapon(). On a swapless host every ctrl->map is NULL, so __swap_cgroup_id_lookup() dereferences NULL + a scaled swp_offset(). Since commit bea67dcc5eea ("mm: attempt to batch free swap entries for zap_pte_range()"), zap_pte_range() -> swap_pte_batch() calls lookup_swap_cgroup_id() on any non-present, non-none PTE that decodes as a real swap entry, without first validating it against swap_info[]. A single PTE corrupted into a type-0 swap entry takes the host down at process exit. We hit this in production on a swapless 6.12.58 host: ~1s of "get_swap_device: Bad swap file entry 3f800204222bb" (do_swap_page() being correctly defensive about the same entry) followed by BUG: unable to handle page fault for address: 000003f800204220 RIP: 0010:lookup_swap_cgroup_id+0x2b/0x60 Call Trace: swap_pte_batch+0xbf/0x230 zap_pte_range+0x4c8/0x780 unmap_page_range+0x190/0x3e0 exit_mmap+0xd9/0x3c0 do_exit+0x20c/0x4b0 syzbot has reported the identical stack. The source of the PTE corruption is a separate bug; this change makes the teardown path as robust as the fault path already is. Every other caller of lookup_swap_cgroup_id() is downstream of a get_swap_device() that has already validated the entry, so the new branch is cold.

See more information about CVE-2026-64416 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	5.5
Vector String:	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Version:	3.1
Attack Vector:	Local
Attack Complexity:	Low
Privileges Required:	Low
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	None
Integrity Impact:	None
Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 10 (kernel-uek)	ELSA-2026-500248	2026-09-04
Oracle Linux version 9 (kernel-uek)	ELSA-2026-500248	2026-09-04