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Linux KernelOperating system · Linux

CVE-2025-39895

MEDIUM · 5.5 CVSS v3.1 Published 2025-10-01
Fix available
A fix is available. Upgrade to 6.6.105 / 6.12.46 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: sched: Fix sched_numa_find_nth_cpu() if mask offline sched_numa_find_nth_cpu() uses a bsearch to look for the 'closest' CPU in sched_domains_numa_masks and given cpus mask. However they might not intersect if all CPUs in the cpus mask are offline. bsearch will return NULL in that case, bail out instead of dereferencing a bogus pointer. The previous behaviour lead to this bug when using maxcpus=4 on an rk3399 (LLLLbb) (i.e. booting with all big CPUs offline): [ 1.422922] Unable to handle kernel paging request at virtual address ffffff8000000000 [ 1.423635] Mem abort info: [ 1.423889] ESR = 0x0000000096000006 [ 1.424227] EC = 0x25: DABT (current EL), IL = 32 bits [ 1.424715] SET = 0, FnV = 0 [ 1.424995] EA = 0, S1PTW = 0 [ 1.425279] FSC = 0x06: level 2 translation fault [ 1.425735] Data abort info: [ 1.425998] ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000 [ 1.426499] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 1.426952] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 1.427428] swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000004a9f000 [ 1.428038] [ffffff8000000000] pgd=18000000f7fff403, p4d=18000000f7fff403, pud=18000000f7fff403, pmd=0000000000000000 [ 1.429014] Internal error: Oops: 0000000096000006 [#1] SMP [ 1.429525] Modules linked in: [ 1.429813] CPU: 3 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.17.0-rc4-dirty #343 PREEMPT [ 1.430559] Hardware name: Pine64 RockPro64 v2.1 (DT) [ 1.431012] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 1.431634] pc : sched_numa_find_nth_cpu+0x2a0/0x488 [ 1.432094] lr : sched_numa_find_nth_cpu+0x284/0x488 [ 1.432543] sp : ffffffc084e1b960 [ 1.432843] x29: ffffffc084e1b960 x28: ffffff80078a8800 x27: ffffffc0846eb1d0 [ 1.433495] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 [ 1.434144] x23: 0000000000000000 x22: fffffffffff7f093 x21: ffffffc081de6378 [ 1.434792] x20: 0000000000000000 x19: 0000000ffff7f093 x18: 00000000ffffffff [ 1.435441] x17: 3030303866666666 x16: 66663d736b73616d x15: ffffffc104e1b5b7 [ 1.436091] x14: 0000000000000000 x13: ffffffc084712860 x12: 0000000000000372 [ 1.436739] x11: 0000000000000126 x10: ffffffc08476a860 x9 : ffffffc084712860 [ 1.437389] x8 : 00000000ffffefff x7 : ffffffc08476a860 x6 : 0000000000000000 [ 1.438036] x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000 [ 1.438683] x2 : 0000000000000000 x1 : ffffffc0846eb000 x0 : ffffff8000407b68 [ 1.439332] Call trace: [ 1.439559] sched_numa_find_nth_cpu+0x2a0/0x488 (P) [ 1.440016] smp_call_function_any+0xc8/0xd0 [ 1.440416] armv8_pmu_init+0x58/0x27c [ 1.440770] armv8_cortex_a72_pmu_init+0x20/0x2c [ 1.441199] arm_pmu_device_probe+0x1e4/0x5e8 [ 1.441603] armv8_pmu_device_probe+0x1c/0x28 [ 1.442007] platform_probe+0x5c/0xac [ 1.442347] really_probe+0xbc/0x298 [ 1.442683] __driver_probe_device+0x78/0x12c [ 1.443087] driver_probe_device+0xdc/0x160 [ 1.443475] __driver_attach+0x94/0x19c [ 1.443833] bus_for_each_dev+0x74/0xd4 [ 1.444190] driver_attach+0x24/0x30 [ 1.444525] bus_add_driver+0xe4/0x208 [ 1.444874] driver_register+0x60/0x128 [ 1.445233] __platform_driver_register+0x24/0x30 [ 1.445662] armv8_pmu_driver_init+0x28/0x4c [ 1.446059] do_one_initcall+0x44/0x25c [ 1.446416] kernel_init_freeable+0x1dc/0x3bc [ 1.446820] kernel_init+0x20/0x1d8 [ 1.447151] ret_from_fork+0x10/0x20 [ 1.447493] Code: 90022e21 f000e5f5 910de2b5 2a1703e2 (f8767803) [ 1.448040] ---[ end trace 0000000000000000 ]--- [ 1.448483] note: swapper/0[1] exited with preempt_count 1 [ 1.449047] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b [ 1.449741] SMP: stopping secondary CPUs [ 1.450105] Kernel Offset: disabled [ 1.450419] CPU features: 0x000000,00080000,20002001,0400421b [ ---truncated---

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.3, < 6.6.105>= 6.7, < 6.12.46>= 6.13, < 6.16.6= 6.17

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.105 / 6.12.46 / 6.16.6 or later
Fixed in 6.6.1056.12.466.16.6
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux kernel 6.6.105+, 6.12.46+, 6.16.6+, or 6.18+ (choose based on your distribution's available stable branches)

  1. Identify the currently running kernel version using 'uname -r' or 'cat /proc/version'
  2. Determine which version range your kernel falls into: >= 6.3 and < 6.6.105, >= 6.7 and < 6.12.46, >= 6.13 and < 6.16.6, or exactly 6.17
  3. Upgrade the Linux kernel to a fixed version: 6.6.105 or later, 6.12.46 or later, 6.16.6 or later, or 6.18 or later
  4. Reboot the system to load the patched kernel
  5. Verify the fix is applied by checking the kernel version after reboot
Caveat Kernel upgrades may require system reboot and could have compatibility implications with custom modules or specific hardware drivers; ensure backup and test in staging if possible

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $2,850. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-39895 in production — separate from our analysis above.

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