CyberSecBulletin
CVE-2026-23271NVD status: Modified

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2026-23271 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 4df1a45819e50993cb351682a6ae8e7ed2d233a0, 4f8d5812337871227bb2c98669a87c306a2f86ef, 5c48fdc4b4623533d86e279f51531a7ba212eb87 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 4df1a45819e50993cb351682a6ae8e7ed2d233a0 or 4f8d5812337871227bb2c98669a87c306a2f86ef or 5c48fdc4b4623533d86e279f51531a7ba212eb87 or 3f89b61dd504c5b6711de9759e053b082f9abf12, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.167 or 6.6.130 or 6.12.77 or 6.18.17, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux592903cdcbf606a838056bae6d03fc557806c914 up to, but not including, 4df1a45819e50993cb351682a6ae8e7ed2d233a0; 592903cdcbf606a838056bae6d03fc557806c914 up to, but not including, 4f8d5812337871227bb2c98669a87c306a2f86ef; 592903cdcbf606a838056bae6d03fc557806c914 up to, but not including, 5c48fdc4b4623533d86e279f51531a7ba212eb87; 592903cdcbf606a838056bae6d03fc557806c914 up to, but not including, 3f89b61dd504c5b6711de9759e053b082f9abf12; 592903cdcbf606a838056bae6d03fc557806c914 up to, but not including, bb190628fe5f2a73ba762a9972ba16c5e895f73e; 592903cdcbf606a838056bae6d03fc557806c914 up to, but not including, c9bc1753b3cc41d0e01fbca7f035258b5f4db0ae; 2.6.314df1a45819e50993cb351682a6ae8e7ed2d233a0, 4f8d5812337871227bb2c98669a87c306a2f86ef, 5c48fdc4b4623533d86e279f51531a7ba212eb87, 3f89b61dd504c5b6711de9759e053b082f9abf12, bb190628fe5f2a73ba762a9972ba16c5e895f73e, c9bc1753b3cc41d0e01fbca7f035258b5f4db0ae
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)V3.1.6 and later; V3.1.5 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)V3.1.6 and later; V3.1.5 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)V3.1.6 and later; V3.1.5 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)V3.1.6 and later; V3.1.5 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
SiemensSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)V3.1.6 and later; V3.1.5 and later; V3.1.7 and laterNot stated
LinuxLinux Kernel2.6.31 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.77; 6.13 up to, but not including, 6.18.17; 6.19 up to, but not including, 6.19.7; 7.06.1.167, 6.6.130, 6.12.77, 6.18.17, 6.19.7

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: perf: Fix __perf_event_overflow() vs perf_remove_from_context() race Make sure that __perf_event_overflow() runs with IRQs disabled for all possible callchains. Specifically the software events can end up running it with only preemption disabled. This opens up a race vs perf_event_exit_event() and friends that will go and free various things the overflow path expects to be present, like the BPF program.

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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