CyberSecBulletin
CVE-2026-78239NVD status: Deferred

Xiiaozet LK100W: Missing Authentication for Critical Functionality

Published Updated By the CyberSecBulletin desk

CVE-2026-78239 is a critical-severity missing authentication for critical functionality vulnerability in Xiiaozet LK100W from Xiiaozet, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 2.1.240 as the first without the flaw, so updating Xiiaozet LK100W to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.77% chance of exploitation within 30 days, higher than 56% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Xiiaozet LK100W to 2.1.240 or a later version.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
XiiaozetXiiaozet LK100Wbefore 2.1.2402.1.240

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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (hq.dhs.gov).

Scoring systemScoreSeverityScored by
CVSS 4.09.3CriticalCNA (hq.dhs.gov)
CVSS 3.19.8CriticalCNA (hq.dhs.gov)

Official description

Xiiaozet LK100W exposes a critical management function that can be invoked without authentication, allowing a remote attacker to enable administrative services that should be restricted. Successful exploitation may permit unauthorized access to the device.

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

The underlying weakness: Missing Authentication for Critical Functionality

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

How developers prevent this class of flaw

  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
  • When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.

More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Xiiaozet LK100W

All Xiiaozet LK100W vulnerabilities

Recent Missing Authentication for Critical Functionality vulnerabilities

Spotted an error? Tell us.