CyberSecBulletin
CVE-2025-68404NVD status: Awaiting Analysis

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

Published Updated By the CyberSecBulletin desk

CVE-2025-68404 is a high-severity time-of-check time-of-use (TOCTOU) race condition vulnerability in QuRouter from QNAP, with a CVSS 4.0 base score of 7.5 out of 10. It can be exploited from the same local network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 2.6.4.001 as the first without the flaw, so updating QuRouter to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.15% 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 QuRouter to 2.6.4.001 or a later version.
  2. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
QNAPQuRouter2.6.x up to, but not including, 2.6.4.0012.6.4.001

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
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Attack requirements
PresentThe target must be in a specific state or configuration for the attack to work.
Privileges required
NoneNo account or login is needed.
User interaction
PassiveA user only needs to do something routine, such as viewing a page.
Confidentiality (vulnerable system)
HighSerious loss of confidentiality on the vulnerable system.
Integrity (vulnerable system)
HighSerious loss of integrity on the vulnerable system.
Availability (vulnerable system)
HighSerious loss of availability on the vulnerable system.
Confidentiality (other systems)
NoneNo loss of confidentiality on systems beyond the vulnerable one.
Integrity (other systems)
NoneNo loss of integrity on systems beyond the vulnerable one.
Availability (other systems)
NoneNo loss of availability on systems beyond the vulnerable one.

Vector: CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA (qnapsecurity.com.tw).

Official description

A time-of-check time-of-use (toctou) race condition vulnerability has been reported to affect QuRouter. If exploited, the vulnerability could allow remote attackers to compromise the security of the system. We have already fixed the vulnerability in the following version: QuRouter 2.6.4.001 and later

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

Other vulnerabilities in QuRouter

All QuRouter vulnerabilities

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

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