CyberSecBulletin
CVE-2026-84409NVD status: Awaiting Analysis

G520 Series: Improper Neutralization of Input During Web Page Generation

Published Updated By the CyberSecBulletin desk

CVE-2026-84409 is a high-severity improper neutralization of input during web page generation vulnerability in G520 Series from Lantronix, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected G520 Series versions: 2.6.0.4R6 stable. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.42% 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. Check which version of G520 Series you run against the affected versions below, and install the vendor's latest release.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  3. 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
LantronixG520 Series2.6.0.4R6 stableNot stated

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
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
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:H/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by CNA (hq.dhs.gov).

Scoring systemScoreSeverityScored by
CVSS 4.07.7HighCNA (hq.dhs.gov)
CVSS 3.17.5HighCNA (hq.dhs.gov)

Official description

The device's update mechanism retrieves metadata for software updates over an unencrypted HTTP connection and stores portions of that metadata for later use. A management interface subsequently returns this stored value in a JSON response, and the web interface responsible for displaying update information inserts that value directly into the page as HTML. This behavior allows attacker‑controlled metadata to be interpreted as script content. In addition, the same authenticated origin provides an interface capable of executing system‑level commands with root privileges. An attacker able to influence update metadata could exploit these conditions to execute arbitrary code within the administrative context of the device.

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

The underlying weakness: Improper Neutralization of Input During Web Page Generation

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

How developers prevent this class of flaw

  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.
  • Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
  • 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.

More Improper Neutralization of Input During Web Page Generation vulnerabilities (CWE-79)

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 G520 Series

All G520 Series vulnerabilities

Recent Improper Neutralization of Input During Web Page Generation vulnerabilities

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