High severity · published Sep 29, 2026
CVE-2026-91191
Lantronix G520 Series Cellular Gateway Improper Verification of Cryptographic Signature
7.5
CVSS
0.2%
EPSS
No
On KEV
Description
The device's update mechanism includes conditions that allow unauthorized software packages to be accepted as authentic. During the boot process, the stock done function disables signature verification in the OPKG configuration before restoring optional packages from a writable, unsigned feed. Separately, the publicly distributed SDK contains the production private key whose corresponding public key is trusted by both stable and beta firmware builds. Either issue undermines package authenticity, and together they allow an attacker to provide packages that appear valid to the system. Even if signature enforcement is restored, the exposed production key enables an attacker to generate signatures that the device will continue to trust. An attacker who can supply a malicious package may be able to execute arbitrary code with root privileges during installation.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 13% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GS
G520 Series · Lantronix
2.6.0.4R6 stable · source: vendor
In the news
VulnerabilityHigh
Lantronix G520 Series Cellular Gateway
View CSAF Summary Successful exploitation of these vulnerabilities could allow an attacker to replace software and execute arbitrary code with root privileges. The following versions of Lantronix G520 Series Cellular Gateway are affected: G520 Series 2.6.0.4R6_stable (CVE-2026-84409, CVE-2026-91191) CVSS Vendor Equipment Vulnerabilities v3 7.5 Lantronix Lantronix G520 Series Cellular Gateway Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), Improper Verification of Cryptographic Signature Background Critical Infrastructure Sectors: Transportation Systems, Energy, Water and Wastewater Systems Countries/Areas Deployed: Worldwide Company Headquarters Location: United States Vulnerabilities Expand All + CVE-2026-84409 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 cond...
Sep 29, 2026·CISA Advisories