CyberSecBulletin
CVE-2026-40058NVD status: Awaiting Analysis

Falcon sensor for Windows: Time-of-check Time-of-use (TOCTOU) Race Condition

Published Updated By the CyberSecBulletin desk

CVE-2026-40058 is a high-severity time-of-check time-of-use (TOCTOU) race condition vulnerability in Falcon sensor for Windows from CrowdStrike, with a CVSS 3.1 base score of 8.8 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 8.10.21408, 7.40.21309, 7.39.21113 as the first without the flaw, so updating Falcon sensor for Windows to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.08% 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 Falcon sensor for Windows to 8.10.21408 or 7.40.21309 or 7.39.21113 or 7.38.21007, whichever matches your release line, or a later version.
  2. Update Laroux Cleanup Tool to 1.4.70.0 or a later version.
  3. Read the advisory on crowdstrike.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
CrowdStrikeFalcon sensor for Windows8.10.0 up to, but not including, 8.10.21408; 7.40.0 up to, but not including, 7.40.21309; 7.39.0 up to, but not including, 7.39.21113; 7.38.0 up to, but not including, 7.38.21007; 7.37.0 up to, but not including, 7.37.20912; 7.36.0 up to, but not including, 7.36.20807; 7.35.0 up to, but not including, 7.35.20712; 7.34.0 up to, but not including, 7.34.20613; and 3 more ranges8.10.21408, 7.40.21309, 7.39.21113, 7.38.21007, 7.37.20912, 7.36.20807
CrowdStrikeLaroux Cleanup Tool1.0.20 up to, but not including, 1.4.70.01.4.70.0

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
ChangedThe attack can reach beyond the vulnerable component into other systems.
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:C/C:H/I:H/A:H. Scored by CNA.

Official description

CrowdStrike released a security update to address a vulnerability in the Falcon sensor for Windows. The vulnerability only exists when the Microsoft Office File Malicious Macro Removal Windows policy setting is enabled and customers remain protected through the Cloud Anti-malware for Microsoft Office Files settings. An update is available immediately for versions 7.34 and above, 7.32 LTS, and 7.16 for Windows 7/2008 R2 systems. The Falcon sensor for Mac, Linux, and Legacy Systems are not affected. This vulnerability could expose an arbitrary file write to protected locations from an unprivileged context, potentially leading to local privilege escalation. The CrowdStrike Laroux Malware Cleanup Tool, based off of the same feature in the CrowdStrike Falcon sensor for Windows, is also affected. An update for this tool is also available immediately.

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

The underlying weakness: Time-of-check Time-of-use (TOCTOU) Race Condition

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How developers prevent this class of flaw

  • The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
  • When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
  • Limit the interleaving of operations on files from multiple processes.

More Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities (CWE-367)

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 Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities

Spotted an error? Tell us.