Local denial of service via sparse KSM mapping
Published Dec 16, 2025 · Updated Dec 16, 2025
Denial of service in Linux kernel KSM allows local users to monopolize ksmd CPU via a sparse mergeable virtual memory area. scan_get_next_rmap_item() checks every page address instead of skipping unmapped holes, so a vast sparsely populated VMA makes ksmd consume a CPU without useful deduplication. KSM must be enabled and the local user must mark the sparse mapping mergeable; the resulting stall interrupts memory deduplication and consumes sustained processor capacity.
Summary
What happened
Denial of service in Linux kernel KSM allows local users to monopolize ksmd CPU via a sparse mergeable virtual memory area. scan_get_next_rmap_item() checks every page address instead of skipping unmapped holes, so a vast sparsely populated VMA makes ksmd consume a CPU without useful deduplication. KSM must be enabled and the local user must mark the sparse mapping mergeable; the resulting stall interrupts memory deduplication and consumes sustained processor capacity.
The record
- CVE
- CVE-2025-68211
- Published
- Dec 16, 2025
- Updated
- Dec 16, 2025
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 16, 2025CVE publishedPublication date reported by the CVE source.
- Dec 16, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.6.32
- Affected versionversion=31dbd01f314364b70c2e026a5793a29a4da8a9dc <74f78421c925b6d17695566f0c5941de57fd44b3
- Affected versionversion=31dbd01f314364b70c2e026a5793a29a4da8a9dc <f5548c318d6520d4fa3c5ed6003eeb710763cbc5
- Affected versionversion=31dbd01f314364b70c2e026a5793a29a4da8a9dc <f62973e0767e4fcd6799087787fca08ca2a85b8c
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream sparse KSM reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo