PT-2025-51624 · Linux+3 · Linux Kernel+3
Published
2025-12-16
·
Updated
2026-05-26
·
CVE-2025-68211
CVSS v3.1
5.5
Medium
| Vector | AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Name of the Vulnerable Software and Affected Versions
Linux kernel (affected versions not specified)
Description
The Linux kernel’s KSM (Kernel Samepage Merging) functionality experienced performance issues when scanning large virtual memory areas with mostly unmapped regions. The
scan get next rmap item() function inefficiently walked every page address within a VMA to locate mergeable pages, leading to high CPU usage without significant deduplication. The issue was addressed by replacing the per-address lookup with a range walk using walk page range(). This allows KSM to skip unmapped holes in a VMA, avoiding unnecessary lookups and improving performance. A test program was provided that demonstrated the issue by creating a 32 TiB mapping with only one populated page, causing ksmd to use 100% CPU for an extended period without deduplicating.Recommendations
At the moment, there is no information about a newer version that contains a fix for this vulnerability.
Exploit
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Related Identifiers
Affected Products
Debian
Linuxmint
Linux Kernel
Ubuntu