CVE-2025-68211
published 2025-12-16CVE-2025-68211: 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…
PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.13%
3.1th percentile
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
#include
#include
/* 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.
Affected
47 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | linux | < linux 6.1.162-1 (bookworm) | linux 6.1.162-1 (bookworm) |
| debian | linux-6.1 | < linux 6.1.162-1 (bookworm) | linux 6.1.162-1 (bookworm) |
| linux | linux | — | — |
| linux | linux | >= 31dbd01f314364b70c2e026a5793a29a4da8a9dc < 220cb3e425e17587f560335924cba9f16a842c64 | 220cb3e425e17587f560335924cba9f16a842c64 |
| linux | linux | >= 31dbd01f314364b70c2e026a5793a29a4da8a9dc < 10644e8839544dd5699c03c8fb1aeeefc41602fd | 10644e8839544dd5699c03c8fb1aeeefc41602fd |
| linux | linux | >= 31dbd01f314364b70c2e026a5793a29a4da8a9dc < 67137b715b7db28d82e4ed07a7092c2fa6ba7adb | 67137b715b7db28d82e4ed07a7092c2fa6ba7adb |
| linux | linux | >= 31dbd01f314364b70c2e026a5793a29a4da8a9dc < 9c2f8a9b68024e5ebb4813665845ec0a95f2eac3 | 9c2f8a9b68024e5ebb4813665845ec0a95f2eac3 |
| linux | linux | >= 31dbd01f314364b70c2e026a5793a29a4da8a9dc < 74f78421c925b6d17695566f0c5941de57fd44b3 | 74f78421c925b6d17695566f0c5941de57fd44b3 |
| linux | linux | >= 31dbd01f314364b70c2e026a5793a29a4da8a9dc < f62973e0767e4fcd6799087787fca08ca2a85b8c | f62973e0767e4fcd6799087787fca08ca2a85b8c |
| linux | linux | >= 31dbd01f314364b70c2e026a5793a29a4da8a9dc < f5548c318d6520d4fa3c5ed6003eeb710763cbc5 | f5548c318d6520d4fa3c5ed6003eeb710763cbc5 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 0 < 5.10.249-1 | 5.10.249-1 |
| linux | linux_kernel | >= 0 < 6.1.162-1 | 6.1.162-1 |
| linux | linux_kernel | >= 0 < 6.12.63-1 | 6.12.63-1 |
| linux | linux_kernel | >= 0 < 6.17.9-1 | 6.17.9-1 |
| linux | linux_kernel | >= 0 < 6.17.0-14.14 | 6.17.0-14.14 |
| linux | linux_kernel | >= 2.6.32 < 5.10.249 | 5.10.249 |
| linux | linux_kernel | >= 5.11 < 5.15.199 | 5.15.199 |
| linux | linux_kernel | >= 5.16 < 6.1.161 | 6.1.161 |
| linux | linux_kernel | >= 6.13 < 6.17.9 | 6.17.9 |
| linux | linux_kernel | >= 6.2 < 6.6.121 | 6.6.121 |
| linux | linux_kernel | >= 6.7 < 6.12.59 | 6.12.59 |
| msrc | azl3_kernel_6.6.117.1-1_on_azure_linux_3.0 | — | — |
| msrc | azl3_kernel_6.6.119.3-1_on_azure_linux_3.0 | — | — |
| msrc | azl3_kernel_6.6.119.3-3_on_azure_linux_3.0 | — | — |
CVSS provenance
nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_ubuntu7.8HIGH
vendor_debian5.5MEDIUM
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
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vendor_redhat·2025-12-16·CVSS 5.5
CVE-2025-68211 [MEDIUM] CWE-606 kernel: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
kernel: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
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
Microsoft
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vendor_msrc·2025-12-09·CVSS 5.5
CVE-2025-68211 [MEDIUM] ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
Mariner: Mariner
Linux: Linux
Customer Action Required: Yes
Remediation: CBL-Mariner Releases
Reference: https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade
Debian
CVE-2025-68211: linux - In the Linux kernel, the following vulnerability has been resolved: ksm: use ra...
vendor_debian·2025·CVSS 5.5
CVE-2025-68211 [MEDIUM] CVE-2025-68211: linux - In the Linux kernel, the following vulnerability has been resolved: ksm: use ra...
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
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OSV
linux-aws, linux-oracle vulnerabilities
osv·2026-02-17
linux-aws, linux-oracle vulnerabilities
linux-aws, linux-oracle vulnerabilities
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and drivers;
- CPU frequency scaling framework;
- Hardware crypto de
OSV
linux-gcp vulnerabilities
osv·2026-02-12
linux-gcp vulnerabilities
linux-gcp vulnerabilities
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and drivers;
- CPU frequency scaling framework;
- Hardware crypto device drivers;
OSV
linux, linux-raspi, linux-realtime vulnerabilities
osv·2026-02-12
linux, linux-raspi, linux-realtime vulnerabilities
linux, linux-raspi, linux-realtime vulnerabilities
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and drivers;
- CPU frequency scaling framework;
- Hardwar
OSV
CVE-2025-68211: 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 Current
osv·2025-12-16·CVSS 5.5
CVE-2025-68211 [MEDIUM] CVE-2025-68211: 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 Current
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
GHSA
GHSA-qhqr-mc3h-hmjp: 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
Curre
ghsa_unreviewed·2025-12-16
CVE-2025-68211 [MEDIUM] GHSA-qhqr-mc3h-hmjp: 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
Curre
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:
#inc
No detection rules found.
No public exploits indexed.
Wiz
CVE-2025-68211 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 5.5
CVE-2025-68211 [MEDIUM] CVE-2025-68211 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2025-68211 :
Linux Kernel vulnerability analysis and mitigation
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 map
Bugzilla
CVE-2025-68211 kernel: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
bugzilla·2025-12-16·CVSS 5.5
CVE-2025-68211 [MEDIUM] CVE-2025-68211 kernel: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
CVE-2025-68211 kernel: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
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
https://git.kernel.org/stable/c/10644e8839544dd5699c03c8fb1aeeefc41602fdhttps://git.kernel.org/stable/c/220cb3e425e17587f560335924cba9f16a842c64https://git.kernel.org/stable/c/67137b715b7db28d82e4ed07a7092c2fa6ba7adbhttps://git.kernel.org/stable/c/74f78421c925b6d17695566f0c5941de57fd44b3https://git.kernel.org/stable/c/9c2f8a9b68024e5ebb4813665845ec0a95f2eac3https://git.kernel.org/stable/c/f5548c318d6520d4fa3c5ed6003eeb710763cbc5https://git.kernel.org/stable/c/f62973e0767e4fcd6799087787fca08ca2a85b8c
2025-12-16
Published