CyberSecBulletin
CVE-2026-43433NVD status: Analyzed

Linux: Time-of-check Time-of-use (TOCTOU) Race Condition

Published Updated By the CyberSecBulletin desk

CVE-2026-43433 is a high-severity time-of-check time-of-use (TOCTOU) race condition 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 e19afb53f7723b3bd22224f2b0c7dcfa70bb973f, 3672141c93b7a0c0132bf5d5021a4b7f1d663aaa, 4cb9e13fec0de7c942f5f927469beb8e48ddd20f 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 0.1% 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 e19afb53f7723b3bd22224f2b0c7dcfa70bb973f or 3672141c93b7a0c0132bf5d5021a4b7f1d663aaa or 4cb9e13fec0de7c942f5f927469beb8e48ddd20f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.18.19 or 6.19.9, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxeafedbc7c050c44744fbdf80bdf3315e860b7513 up to, but not including, e19afb53f7723b3bd22224f2b0c7dcfa70bb973f; eafedbc7c050c44744fbdf80bdf3315e860b7513 up to, but not including, 3672141c93b7a0c0132bf5d5021a4b7f1d663aaa; eafedbc7c050c44744fbdf80bdf3315e860b7513 up to, but not including, 4cb9e13fec0de7c942f5f927469beb8e48ddd20f; 6.18e19afb53f7723b3bd22224f2b0c7dcfa70bb973f, 3672141c93b7a0c0132bf5d5021a4b7f1d663aaa, 4cb9e13fec0de7c942f5f927469beb8e48ddd20f
LinuxLinux Kernel6.18 up to, but not including, 6.18.19; 6.19 up to, but not including, 6.19.9; 7.06.18.19, 6.19.9

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: rust_binder: avoid reading the written value in offsets array When sending a transaction, its offsets array is first copied into the target proc's vma, and then the values are read back from there. This is normally fine because the vma is a read-only mapping, so the target process cannot change the value under us. However, if the target process somehow gains the ability to write to its own vma, it could change the offset before it's read back, causing the kernel to misinterpret what the sender meant. If the sender happens to send a payload with a specific shape, this could in the worst case lead to the receiver being able to privilege escalate into the sender. The intent is that gaining the ability to change the read-only vma of your own process should not be exploitable, so remove this TOCTOU read even though it's unexploitable without another Binder bug.

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. Record last changed materially (score, affected products, status or references).

References

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

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