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NVD / CVE Program· CNA Linux

CVE-2025-68211: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.14% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 10644e8839544dd5699c03c8fb1aeeefc41602fd, 220cb3e425e17587f560335924cba9f16a842c64, 67137b715b7db28d82e4ed07a7092c2fa6ba7adb.

Low priority for now. Upgrade to Linux Linux 10644e8839544dd5699c03c8fb1aeeefc41602fd, 220cb3e425e17587f560335924cba9f16a842c64, 67137b715b7db28d82e4ed07a7092c2fa6ba7adb or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item Currently, scan_get_next_rmap_item() walks every page address in a VMA to locate mergeable pages. This becomes highly inefficient when scanning large virtual memory areas that contain mostly unmapped regions, causing ksmd to use large amount of cpu without deduplicating much pages. This patch replaces the per-address lookup with a range walk using walk_page_range(). The range walker allows KSM to skip over entire unmapped holes in a VMA, avoiding unnecessary lookups. This problem was previously discussed in [1]. Consider the following test program which creates a 32 TiB mapping in the virtual address space but only populates a single page: #include <unistd.h> #include <stdio.h> #include <sys/mman.h> /* 32 TiB */ const size_t size = 32ul * 1024 * 1024 * 1024 * 1024; int main() { char *area = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_NORESERVE | MAP_PRIVATE | MAP_ANON, -1, 0); if (area == MAP_FAILED) { perror("mmap() failed\n"); return -1; } /* Populate a single page such that we get an anon_vma. */ *area = 0; /* Enable KSM. */ madvise(area, size, MADV_MERGEABLE); pause(); return 0; } $ ./ksm-sparse & $ echo 1 > /sys/kernel/mm/ksm/run Without this patch ksmd uses 100% of the cpu for a long time (more then 1 hour in my test machine) scanning all the 32 TiB virtual address space that contain only one mapped page. This makes ksmd essentially deadlocked not able to deduplicate anything of value. With this patch ksmd walks only the one mapped page and skips the rest of the 32 TiB virtual address space, making the scan fast using little cpu.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Dec 16, 2025
Updated
Oct 14, 2026
EPSS
0.1% · 3th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

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  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.32 and later · before 5.10.249
  • linux linux kernel5.11 and later · before 5.15.199
  • linux linux kernel5.16 and later · before 6.1.161
  • linux linux kernel6.2 and later · before 6.6.121
  • linux linux kernel6.7 and later · before 6.12.59
  • linux linux kernel6.13 and later · before 6.17.9
  • linux linux kernel6.18

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.32affected
    • 31dbd01f314364b70c2e026a5793a29a4da8a9dc and later · before 220cb3e425e17587f560335924cba9f16a842c64affected · git
    • 31dbd01f314364b70c2e026a5793a29a4da8a9dc and later · before 10644e8839544dd5699c03c8fb1aeeefc41602fdaffected · git
    • 31dbd01f314364b70c2e026a5793a29a4da8a9dc and later · before 67137b715b7db28d82e4ed07a7092c2fa6ba7adbaffected · git
    • 31dbd01f314364b70c2e026a5793a29a4da8a9dc and later · before 9c2f8a9b68024e5ebb4813665845ec0a95f2eac3affected · git
    • 31dbd01f314364b70c2e026a5793a29a4da8a9dc and later · before 74f78421c925b6d17695566f0c5941de57fd44b3affected · git
    • 31dbd01f314364b70c2e026a5793a29a4da8a9dc and later · before f62973e0767e4fcd6799087787fca08ca2a85b8caffected · git
    • 31dbd01f314364b70c2e026a5793a29a4da8a9dc and later · before f5548c318d6520d4fa3c5ed6003eeb710763cbc5affected · git
    • before 2.6.32not affected · semver
    • 5.10.249 and later · up to and including 5.10.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.42.1.el10_26.12.0-211.42.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2025-13316Nov 19, 2025 · Hard-coded encryption keys in Twonky Server
    60This week
  • ← EarlierCVE-2025-40251Dec 4, 2025 · devlink: rate: Unset parent pointer in devl_rate_nodes_destroy
    22Monitor
  • Later →CVE-2025-68214Dec 16, 2025 · timers: Fix NULL function pointer race in timer_shutdown_sync()
    18Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux10644e8839544dd5699c03c8fb1aeeefc41602fdVendor (CNA)
Linux Linux220cb3e425e17587f560335924cba9f16a842c64Vendor (CNA)
Linux Linux67137b715b7db28d82e4ed07a7092c2fa6ba7adbVendor (CNA)
Linux Linux74f78421c925b6d17695566f0c5941de57fd44b3Vendor (CNA)
Linux Linux9c2f8a9b68024e5ebb4813665845ec0a95f2eac3Vendor (CNA)
Linux Linuxf5548c318d6520d4fa3c5ed6003eeb710763cbc5Vendor (CNA)
Linux Linuxf62973e0767e4fcd6799087787fca08ca2a85b8cVendor (CNA)
almalinux:kernel6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.42.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.1.162-1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel-matched0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debuginfo0:6.12.0-211.42.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+3

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records