CyberSecBulletin
CVE-2025-71078NVD status: Modified

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2025-71078 is a high-severity concurrent execution using shared resource with improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 01324c0328181b94cf390bda22ff91c75126ea57, 2e9a95d60f1df7b57618fd5ef057aef331575bd2, c9f865022a1823d814032a09906e91e4701a35fc as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.11% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 01324c0328181b94cf390bda22ff91c75126ea57 or 2e9a95d60f1df7b57618fd5ef057aef331575bd2 or c9f865022a1823d814032a09906e91e4701a35fc or b13a3dbfa196af68eae2031f209743735ad416bf, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.248 or 5.15.198 or 6.1.160 or 6.6.120, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux5434ae74629af58ad0fc27143a9ea435f7734410 up to, but not including, 01324c0328181b94cf390bda22ff91c75126ea57; 5434ae74629af58ad0fc27143a9ea435f7734410 up to, but not including, 2e9a95d60f1df7b57618fd5ef057aef331575bd2; 5434ae74629af58ad0fc27143a9ea435f7734410 up to, but not including, c9f865022a1823d814032a09906e91e4701a35fc; 5434ae74629af58ad0fc27143a9ea435f7734410 up to, but not including, b13a3dbfa196af68eae2031f209743735ad416bf; 5434ae74629af58ad0fc27143a9ea435f7734410 up to, but not including, 895123c309a34d2cfccf7812b41e17261a3a6f37; 5434ae74629af58ad0fc27143a9ea435f7734410 up to, but not including, 4ae1e46d8a290319f33f71a2710a1382ba5431e8; 5434ae74629af58ad0fc27143a9ea435f7734410 up to, but not including, 00312419f0863964625d6dcda8183f96849412c6; 4.2001324c0328181b94cf390bda22ff91c75126ea57, 2e9a95d60f1df7b57618fd5ef057aef331575bd2, c9f865022a1823d814032a09906e91e4701a35fc, b13a3dbfa196af68eae2031f209743735ad416bf, 895123c309a34d2cfccf7812b41e17261a3a6f37, 4ae1e46d8a290319f33f71a2710a1382ba5431e8
LinuxLinux Kernel4.20.1 up to, but not including, 5.10.248; 5.11 up to, but not including, 5.15.198; 5.16 up to, but not including, 6.1.160; 6.2 up to, but not including, 6.6.120; 6.7 up to, but not including, 6.12.64; 6.13 up to, but not including, 6.18.4; 4.20; 6.195.10.248, 5.15.198, 6.1.160, 6.6.120, 6.12.64, 6.18.4

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: powerpc/64s/slb: Fix SLB multihit issue during SLB preload On systems using the hash MMU, there is a software SLB preload cache that mirrors the entries loaded into the hardware SLB buffer. This preload cache is subject to periodic eviction — typically after every 256 context switches — to remove old entry. To optimize performance, the kernel skips switch_mmu_context() in switch_mm_irqs_off() when the prev and next mm_struct are the same. However, on hash MMU systems, this can lead to inconsistencies between the hardware SLB and the software preload cache. If an SLB entry for a process is evicted from the software cache on one CPU, and the same process later runs on another CPU without executing switch_mmu_context(), the hardware SLB may retain stale entries. If the kernel then attempts to reload that entry, it can trigger an SLB multi-hit error. The following timeline shows how stale SLB entries are created and can cause a multi-hit error when a process moves between CPUs without a MMU context switch. CPU 0 CPU 1 ----- ----- Process P exec swapper/1 load_elf_binary begin_new_exc activate_mm switch_mm_irqs_off switch_mmu_context switch_slb /* * This invalidates all * the entries in the HW * and setup the new HW * SLB entries as per the * preload cache. */ context_switch sched_migrate_task migrates process P to cpu-1 Process swapper/0 context switch (to process P) (uses mm_struct of Process P) switch_mm_irqs_off() switch_slb load_slb++ /* * load_slb becomes 0 here * and we evict an entry from * the preload cache with * preload_age(). We still * keep HW SLB and preload * cache in sync, that is * because all HW SLB entries * anyways gets evicted in * switch_slb during SLBIA. * We then only add those * entries back in HW SLB, * which are currently * present in preload_cache * (after eviction). */ load_elf_binary continues... setup_new_exec() slb_setup_new_exec() sched_switch event sched_migrate_task migrates process P to cpu-0 context_switch from swapper/0 to Process P switch_mm_irqs_off() /* * Since both prev and next mm struct are same we don't call * switch_mmu_context(). This will cause the HW SLB and SW preload * cache to go out of sync in preload_new_slb_context. Because there * was an SLB entry which was evicted from both HW and preload cache * on cpu-1. Now later in preload_new_slb_context(), when we will try * to add the same preload entry again, we will add this to the SW * preload cache and then will add it to the HW SLB. Since on cpu-0 * this entry was never invalidated, hence adding this entry to the HW * SLB will cause a SLB multi-hit error. */ load_elf_binary cont ---truncated---

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How developers prevent this class of flaw

  • In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
  • Use thread-safe capabilities such as the data access abstraction in Spring.
  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

More Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities (CWE-362)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities

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